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LeetCode

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Solutions

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#	Solution	Tags	Difficulty	Remark
0001	Two Sum	Array,Hash Table	Easy
0002	Add Two Numbers	Recursion,Linked List,Math	Medium
0003	Longest Substring Without Repeating Characters	Hash Table,String,Sliding Window	Medium
0004	Median of Two Sorted Arrays	Array,Binary Search,Divide and Conquer	Hard
0005	Longest Palindromic Substring	String,Dynamic Programming	Medium
0006	ZigZag Conversion	String	Medium
0007	Reverse Integer	Math	Easy
0008	String to Integer (atoi)	String	Medium
0009	Palindrome Number	Math	Easy
0010	Regular Expression Matching	Recursion,String,Dynamic Programming	Hard
0011	Container With Most Water	Greedy,Array,Two Pointers	Medium
0012	Integer to Roman	Hash Table,Math,String	Medium
0013	Roman to Integer	Hash Table,Math,String	Easy
0014	Longest Common Prefix	String	Easy
0015	3Sum	Array,Two Pointers,Sorting	Medium
0016	3Sum Closest	Array,Two Pointers,Sorting	Medium
0017	Letter Combinations of a Phone Number	Hash Table,String,Backtracking	Medium
0018	4Sum	Array,Two Pointers,Sorting	Medium
0019	Remove Nth Node From End of List	Linked List,Two Pointers	Medium
0020	Valid Parentheses	Stack,String	Easy
0021	Merge Two Sorted Lists	Recursion,Linked List	Easy
0022	Generate Parentheses	String,Dynamic Programming,Backtracking	Medium
0023	Merge k Sorted Lists	Linked List,Divide and Conquer,Heap (Priority Queue),Merge Sort	Hard
0024	Swap Nodes in Pairs	Recursion,Linked List	Medium
0025	Reverse Nodes in k-Group	Recursion,Linked List	Hard
0026	Remove Duplicates from Sorted Array	Array,Two Pointers	Easy
0027	Remove Element	Array,Two Pointers	Easy
0028	Implement strStr()	Two Pointers,String,String Matching	Easy
0029	Divide Two Integers	Bit Manipulation,Math	Medium
0030	Substring with Concatenation of All Words	Hash Table,String,Sliding Window	Hard
0063	Unique Paths II	Array,Dynamic Programming,Matrix	Medium
0064	Minimum Path Sum	Array,Dynamic Programming,Matrix	Medium
0065	Valid Number	String	Hard
0066	Plus One	Array,Math	Easy
0067	Add Binary	Bit Manipulation,Math,String,Simulation	Easy
0068	Text Justification	String,Simulation	Hard
0069	Sqrt(x)	Math,Binary Search	Easy
0070	Climbing Stairs	Memoization,Math,Dynamic Programming	Easy
0071	Simplify Path	Stack,String	Medium
0072	Edit Distance	String,Dynamic Programming	Hard
0073	Set Matrix Zeroes	Array,Hash Table,Matrix	Medium
0074	Search a 2D Matrix	Array,Binary Search,Matrix	Medium
0075	Sort Colors	Array,Two Pointers,Sorting	Medium
0076	Minimum Window Substring	Hash Table,String,Sliding Window	Hard
0077	Combinations	Array,Backtracking	Medium
0078	Subsets	Bit Manipulation,Array,Backtracking	Medium
0079	Word Search	Array,Backtracking,Matrix	Medium
0080	Remove Duplicates from Sorted Array II	Array,Two Pointers	Medium
0086	Partition List	Linked List,Two Pointers	Medium
0124	Binary Tree Maximum Path Sum	Tree,Depth-First Search,Dynamic Programming,Binary Tree	Hard
0145	Binary Tree Postorder Traversal	Stack,Tree,Depth-First Search,Binary Tree	Easy
0173	Binary Search Tree Iterator	Stack,Tree,Design,Binary Search Tree,Binary Tree,Iterator	Medium
0174	Dungeon Game	Array,Dynamic Programming,Matrix	Hard
0175	Combine Two Tables	Database	Easy
0176	Second Highest Salary	Database	Medium
0177	Nth Highest Salary	Database	Medium
0178	Rank Scores	Database	Medium
0179	Largest Number	Greedy,String,Sorting	Medium
0180	Consecutive Numbers	Database	Medium
0186	Reverse Words in a String II	Two Pointers,String	Medium	🔒
0195	Tenth Line	Shell	Easy
0196	Delete Duplicate Emails	Database	Easy
0197	Rising Temperature	Database	Easy
0198	House Robber	Array,Dynamic Programming	Medium
0199	Binary Tree Right Side View	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0200	Number of Islands	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
0201	Bitwise AND of Numbers Range	Bit Manipulation	Medium
0202	Happy Number	Hash Table,Math,Two Pointers	Easy
0203	Remove Linked List Elements	Recursion,Linked List	Easy
0204	Count Primes	Array,Math,Enumeration,Number Theory	Medium
0205	Isomorphic Strings	Hash Table,String	Easy
0206	Reverse Linked List	Recursion,Linked List	Easy
0207	Course Schedule	Depth-First Search,Breadth-First Search,Graph,Topological Sort	Medium
0208	Implement Trie (Prefix Tree)	Design,Trie,Hash Table,String	Medium
0209	Minimum Size Subarray Sum	Array,Binary Search,Prefix Sum,Sliding Window	Medium
0210	Course Schedule II	Depth-First Search,Breadth-First Search,Graph,Topological Sort	Medium
0211	Design Add and Search Words Data Structure	Depth-First Search,Design,Trie,String	Medium
0212	Word Search II	Trie,Array,String,Backtracking,Matrix	Hard
0213	House Robber II	Array,Dynamic Programming	Medium
0214	Shortest Palindrome	String,String Matching,Hash Function,Rolling Hash	Hard
0215	Kth Largest Element in an Array	Array,Divide and Conquer,Quickselect,Sorting,Heap (Priority Queue)	Medium
0216	Combination Sum III	Array,Backtracking	Medium
0217	Contains Duplicate	Array,Hash Table,Sorting	Easy
0218	The Skyline Problem	Binary Indexed Tree,Segment Tree,Array,Divide and Conquer,Ordered Set,Line Sweep,Heap (Priority Queue)	Hard
0219	Contains Duplicate II	Array,Hash Table,Sliding Window	Easy
0220	Contains Duplicate III	Array,Bucket Sort,Ordered Set,Sorting,Sliding Window	Medium
0221	Maximal Square	Array,Dynamic Programming,Matrix	Medium
0222	Count Complete Tree Nodes	Tree,Depth-First Search,Binary Search,Binary Tree	Medium
0223	Rectangle Area	Geometry,Math	Medium
0224	Basic Calculator	Stack,Recursion,Math,String	Hard
0225	Implement Stack using Queues	Stack,Design,Queue	Easy
0226	Invert Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0227	Basic Calculator II	Stack,Math,String	Medium
0228	Summary Ranges	Array	Easy
0229	Majority Element II	Array,Hash Table,Counting,Sorting	Medium
0230	Kth Smallest Element in a BST	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
0246	Strobogrammatic Number	Hash Table,Two Pointers,String	Easy	🔒
0262	Trips and Users	Database	Hard
0263	Ugly Number	Math	Easy
0264	Ugly Number II	Hash Table,Math,Dynamic Programming,Heap (Priority Queue)	Medium
0265	Paint House II	Array,Dynamic Programming	Hard	🔒
0266	Palindrome Permutation	Bit Manipulation,Hash Table,String	Easy	🔒
0267	Palindrome Permutation II	Hash Table,String,Backtracking	Medium	🔒
0268	Missing Number	Bit Manipulation,Array,Hash Table,Math,Sorting	Easy
0269	Alien Dictionary	Depth-First Search,Breadth-First Search,Graph,Topological Sort,Array,String	Hard	🔒
0270	Closest Binary Search Tree Value	Tree,Depth-First Search,Binary Search Tree,Binary Search,Binary Tree	Easy	🔒
0271	Encode and Decode Strings	Design,Array,String	Medium	🔒
0272	Closest Binary Search Tree Value II	Stack,Tree,Depth-First Search,Binary Search Tree,Two Pointers,Binary Tree,Heap (Priority Queue)	Hard	🔒
0273	Integer to English Words	Recursion,Math,String	Hard
0274	H-Index	Array,Counting Sort,Sorting	Medium
0275	H-Index II	Array,Binary Search	Medium
0276	Paint Fence	Dynamic Programming	Medium	🔒
0277	Find the Celebrity	Greedy,Graph,Two Pointers,Interactive	Medium	🔒
0278	First Bad Version	Binary Search,Interactive	Easy
0279	Perfect Squares	Breadth-First Search,Math,Dynamic Programming	Medium
0280	Wiggle Sort	Greedy,Array,Sorting	Medium	🔒
0290	Word Pattern	Hash Table,String	Easy
0299	Bulls and Cows	Hash Table,String,Counting	Medium
0320	Generalized Abbreviation	Bit Manipulation,String,Backtracking	Medium	🔒
0373	Find K Pairs with Smallest Sums	Array,Heap (Priority Queue)	Medium
0374	Guess Number Higher or Lower	Binary Search,Interactive	Easy
0375	Guess Number Higher or Lower II	Math,Dynamic Programming,Game Theory	Medium
0376	Wiggle Subsequence	Greedy,Array,Dynamic Programming	Medium
0377	Combination Sum IV	Array,Dynamic Programming	Medium
0378	Kth Smallest Element in a Sorted Matrix	Array,Binary Search,Matrix,Sorting,Heap (Priority Queue)	Medium
0379	Design Phone Directory	Design,Queue,Array,Hash Table,Linked List	Medium	🔒
0380	Insert Delete GetRandom O(1)	Design,Array,Hash Table,Math,Randomized	Medium
0383	Ransom Note	Hash Table,String,Counting	Easy
0394	Decode String	Stack,Recursion,String	Medium
0398	Random Pick Index	Reservoir Sampling,Hash Table,Math,Randomized	Medium
0399	Evaluate Division	Depth-First Search,Breadth-First Search,Union Find,Graph,Array,Shortest Path	Medium
0400	Nth Digit	Math,Binary Search	Medium
0401	Binary Watch	Bit Manipulation,Backtracking	Easy
0402	Remove K Digits	Stack,Greedy,String,Monotonic Stack	Medium
0403	Frog Jump	Array,Dynamic Programming	Hard
0404	Sum of Left Leaves	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0405	Convert a Number to Hexadecimal	Bit Manipulation,Math	Easy
0406	Queue Reconstruction by Height	Greedy,Array,Sorting	Medium
0407	Trapping Rain Water II	Breadth-First Search,Array,Matrix,Heap (Priority Queue)	Hard
0408	Valid Word Abbreviation	Two Pointers,String	Easy	🔒
0409	Longest Palindrome	Greedy,Hash Table,String	Easy
0410	Split Array Largest Sum	Greedy,Array,Binary Search,Dynamic Programming	Hard
0411	Minimum Unique Word Abbreviation	Bit Manipulation,String,Backtracking	Hard	🔒
0412	Fizz Buzz	Math,String,Simulation	Easy
0413	Arithmetic Slices	Array,Dynamic Programming	Medium
0414	Third Maximum Number	Array,Sorting	Easy
0415	Add Strings	Math,String,Simulation	Easy
0416	Partition Equal Subset Sum	Array,Dynamic Programming	Medium
0417	Pacific Atlantic Water Flow	Depth-First Search,Breadth-First Search,Array,Matrix	Medium
0418	Sentence Screen Fitting	String,Dynamic Programming	Medium	🔒
0419	Battleships in a Board	Depth-First Search,Array,Matrix	Medium
0420	Strong Password Checker	Greedy,String,Heap (Priority Queue)	Hard
0421	Maximum XOR of Two Numbers in an Array	Bit Manipulation,Trie,Array,Hash Table	Medium
0422	Valid Word Square	Array,Matrix	Easy	🔒
0423	Reconstruct Original Digits from English	Hash Table,Math,String	Medium
0424	Longest Repeating Character Replacement	Hash Table,String,Sliding Window	Medium
0425	Word Squares	Trie,Array,String,Backtracking	Hard	🔒
0426	Convert Binary Search Tree to Sorted Doubly Linked List	Stack,Tree,Depth-First Search,Binary Search Tree,Linked List,Binary Tree,Doubly-Linked List	Medium	🔒
0430	Flatten a Multilevel Doubly Linked List	Depth-First Search,Linked List,Doubly-Linked List	Medium
0432	All O`one Data Structure	Design,Hash Table,Linked List,Doubly-Linked List	Hard
0433	Minimum Genetic Mutation	Breadth-First Search,Hash Table,String	Medium
0434	Number of Segments in a String	String	Easy
0435	Non-overlapping Intervals	Greedy,Array,Dynamic Programming,Sorting	Medium
0436	Find Right Interval	Array,Binary Search,Sorting	Medium
0440	K-th Smallest in Lexicographical Order	Trie	Hard
0447	Number of Boomerangs	Array,Hash Table,Math	Medium
0448	Find All Numbers Disappeared in an Array	Array,Hash Table	Easy
0449	Serialize and Deserialize BST	Tree,Depth-First Search,Breadth-First Search,Design,Binary Search Tree,String,Binary Tree	Medium
0450	Delete Node in a BST	Tree,Binary Search Tree,Binary Tree	Medium
0451	Sort Characters By Frequency	Hash Table,String,Bucket Sort,Counting,Sorting,Heap (Priority Queue)	Medium
0452	Minimum Number of Arrows to Burst Balloons	Greedy,Array,Sorting	Medium
0453	Minimum Moves to Equal Array Elements	Array,Math	Easy
0454	4Sum II	Array,Hash Table	Medium
0455	Assign Cookies	Greedy,Array,Sorting	Easy
0456	132 Pattern	Stack,Array,Binary Search,Ordered Set,Monotonic Stack	Medium
0457	Circular Array Loop	Array,Hash Table,Two Pointers	Medium
0458	Poor Pigs	Math,Dynamic Programming,Combinatorics	Hard
0459	Repeated Substring Pattern	String,String Matching	Easy
0460	LFU Cache	Design,Hash Table,Linked List,Doubly-Linked List	Hard
0461	Hamming Distance	Bit Manipulation	Easy
0462	Minimum Moves to Equal Array Elements II	Array,Math,Sorting	Medium
0463	Island Perimeter	Depth-First Search,Breadth-First Search,Array,Matrix	Easy
0464	Can I Win	Bit Manipulation,Memoization,Math,Dynamic Programming,Bitmask,Game Theory	Medium
0465	Optimal Account Balancing	Array,Backtracking	Hard	🔒
0466	Count The Repetitions	String,Dynamic Programming	Hard
0467	Unique Substrings in Wraparound String	String,Dynamic Programming	Medium
0468	Validate IP Address	String	Medium
0469	Convex Polygon	Geometry,Math	Medium	🔒
0470	Implement Rand10() Using Rand7()	Math,Rejection Sampling,Probability and Statistics,Randomized	Medium
0471	Encode String with Shortest Length	String,Dynamic Programming	Hard	🔒
0472	Concatenated Words	Depth-First Search,Trie,String,Dynamic Programming	Hard
0473	Matchsticks to Square	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Medium
0474	Ones and Zeroes	Array,String,Dynamic Programming	Medium
0475	Heaters	Array,Binary Search,Sorting	Medium
0476	Number Complement	Bit Manipulation	Easy
0477	Total Hamming Distance	Bit Manipulation,Array,Math	Medium
0478	Generate Random Point in a Circle	Geometry,Math,Rejection Sampling,Randomized	Medium
0479	Largest Palindrome Product	Math	Hard
0480	Sliding Window Median	Array,Hash Table,Sliding Window,Heap (Priority Queue)	Hard
0481	Magical String	Two Pointers,String	Medium
0482	License Key Formatting	String	Easy
0483	Smallest Good Base	Math,Binary Search	Hard
0484	Find Permutation	Stack,Greedy,Array	Medium	🔒
0485	Max Consecutive Ones	Array	Easy
0486	Predict the Winner	Recursion,Array,Math,Dynamic Programming,Game Theory	Medium
0487	Max Consecutive Ones II	Array,Dynamic Programming,Sliding Window	Medium	🔒
0488	Zuma Game	String,Backtracking	Hard
0489	Robot Room Cleaner	Backtracking,Interactive	Hard	🔒
0494	Target Sum	Array,Dynamic Programming,Backtracking	Medium
0497	Random Point in Non-overlapping Rectangles	Reservoir Sampling,Math,Binary Search,Ordered Set,Prefix Sum,Randomized	Medium
0509	Fibonacci Number	Recursion,Memoization,Math,Dynamic Programming	Easy
0519	Random Flip Matrix	Reservoir Sampling,Hash Table,Math,Randomized	Medium
0528	Random Pick with Weight	Math,Binary Search,Prefix Sum,Randomized	Medium
0529	Minesweeper	Depth-First Search,Breadth-First Search,Array,Matrix	Medium
0530	Minimum Absolute Difference in BST	Tree,Depth-First Search,Breadth-First Search,Binary Search Tree,Binary Tree	Easy
0531	Lonely Pixel I	Array,Hash Table,Matrix	Medium	🔒
0532	K-diff Pairs in an Array	Array,Hash Table,Two Pointers,Binary Search,Sorting	Medium
0533	Lonely Pixel II	Array,Hash Table,Matrix	Medium	🔒
0535	Encode and Decode TinyURL	Design,Hash Table,String,Hash Function	Medium
0536	Construct Binary Tree from String	Tree,Depth-First Search,String,Binary Tree	Medium	🔒
0537	Complex Number Multiplication	Math,String,Simulation	Medium
0538	Convert BST to Greater Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
0539	Minimum Time Difference	Array,Math,String,Sorting	Medium
0540	Single Element in a Sorted Array	Array,Binary Search	Medium
0541	Reverse String II	Two Pointers,String	Easy
0542	01 Matrix	Breadth-First Search,Array,Dynamic Programming,Matrix	Medium
0547	Number of Provinces	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0558	Logical OR of Two Binary Grids Represented as Quad-Trees	Tree,Divide and Conquer	Medium
0559	Maximum Depth of N-ary Tree	Tree,Depth-First Search,Breadth-First Search	Easy
0560	Subarray Sum Equals K	Array,Hash Table,Prefix Sum	Medium
0568	Maximum Vacation Days	Array,Dynamic Programming,Matrix	Hard	🔒
0578	Get Highest Answer Rate Question	Database	Medium	🔒
0589	N-ary Tree Preorder Traversal	Stack,Tree,Depth-First Search	Easy
0590	N-ary Tree Postorder Traversal	Stack,Tree,Depth-First Search	Easy
0602	Friend Requests II Who Has the Most Friends	Database	Medium	🔒
0610	Triangle Judgement	Database	Easy	🔒
0611	Valid Triangle Number	Greedy,Array,Two Pointers,Binary Search,Sorting	Medium
0612	Shortest Distance in a Plane	Database	Medium	🔒
0613	Shortest Distance in a Line	Database	Easy	🔒
0614	Second Degree Follower	Database	Medium	🔒
0615	Average Salary Departments VS Company	Database	Hard	🔒
0616	Add Bold Tag in String	Trie,Array,Hash Table,String,String Matching	Medium	🔒
0617	Merge Two Binary Trees	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0618	Students Report By Geography	Database	Hard	🔒
0619	Biggest Single Number	Database	Easy	🔒
0620	Not Boring Movies	Database	Easy
0621	Task Scheduler	Greedy,Array,Hash Table,Counting,Sorting,Heap (Priority Queue)	Medium
0622	Design Circular Queue	Design,Queue,Array,Linked List	Medium
0623	Add One Row to Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0624	Maximum Distance in Arrays	Greedy,Array	Medium	🔒
0625	Minimum Factorization	Greedy,Math	Medium	🔒
0626	Exchange Seats	Database	Medium
0627	Swap Salary	Database	Easy
0628	Maximum Product of Three Numbers	Array,Math,Sorting	Easy
0629	K Inverse Pairs Array	Dynamic Programming	Hard
0630	Course Schedule III	Greedy,Array,Heap (Priority Queue)	Hard
0631	Design Excel Sum Formula	Graph,Design,Topological Sort	Hard	🔒
0632	Smallest Range Covering Elements from K Lists	Greedy,Array,Hash Table,Sorting,Sliding Window,Heap (Priority Queue)	Hard
0633	Sum of Square Numbers	Math,Two Pointers,Binary Search	Medium
0634	Find the Derangement of An Array	Math,Dynamic Programming	Medium	🔒
0635	Design Log Storage System	Design,Hash Table,String,Ordered Set	Medium	🔒
0636	Exclusive Time of Functions	Stack,Array	Medium
0637	Average of Levels in Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0638	Shopping Offers	Bit Manipulation,Memoization,Array,Dynamic Programming,Backtracking,Bitmask	Medium
0639	Decode Ways II	String,Dynamic Programming	Hard
0640	Solve the Equation	Math,String,Simulation	Medium
0642	Design Search Autocomplete System	Design,Trie,String,Data Stream	Hard	🔒
0643	Maximum Average Subarray I	Array,Sliding Window	Easy
0644	Maximum Average Subarray II	Array,Binary Search	Hard	🔒
0645	Set Mismatch	Bit Manipulation,Array,Hash Table,Sorting	Easy
0646	Maximum Length of Pair Chain	Greedy,Array,Dynamic Programming,Sorting	Medium
0647	Palindromic Substrings	String,Dynamic Programming	Medium
0648	Replace Words	Trie,Array,Hash Table,String	Medium
0654	Maximum Binary Tree	Stack,Tree,Array,Divide and Conquer,Binary Tree,Monotonic Stack	Medium
0662	Maximum Width of Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0663	Equal Tree Partition	Tree,Depth-First Search,Binary Tree	Medium	🔒
0664	Strange Printer	String,Dynamic Programming	Hard
0665	Non-decreasing Array	Array	Medium
0666	Path Sum IV	Tree,Depth-First Search,Array,Binary Tree	Medium	🔒
0667	Beautiful Arrangement II	Array,Math	Medium
0668	Kth Smallest Number in Multiplication Table	Binary Search	Hard
0669	Trim a Binary Search Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
0670	Maximum Swap	Greedy,Math	Medium
0671	Second Minimum Node In a Binary Tree	Tree,Depth-First Search,Binary Tree	Easy
0672	Bulb Switcher II	Bit Manipulation,Depth-First Search,Breadth-First Search,Math	Medium
0673	Number of Longest Increasing Subsequence	Binary Indexed Tree,Segment Tree,Array,Dynamic Programming	Medium
0674	Longest Continuous Increasing Subsequence	Array	Easy
0675	Cut Off Trees for Golf Event	Breadth-First Search,Array,Matrix,Heap (Priority Queue)	Hard
0676	Implement Magic Dictionary	Design,Trie,Hash Table,String	Medium
0677	Map Sum Pairs	Design,Trie,Hash Table,String	Medium
0678	Valid Parenthesis String	Stack,Greedy,String,Dynamic Programming	Medium
0679	24 Game	Array,Math,Backtracking	Hard
0680	Valid Palindrome II	Greedy,Two Pointers,String	Easy
0681	Next Closest Time	String,Enumeration	Medium	🔒
0682	Baseball Game	Stack,Array,Simulation	Easy
0683	K Empty Slots	Binary Indexed Tree,Array,Ordered Set,Sliding Window	Hard	🔒
0684	Redundant Connection	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0685	Redundant Connection II	Depth-First Search,Breadth-First Search,Union Find,Graph	Hard
0686	Repeated String Match	String,String Matching	Medium
0687	Longest Univalue Path	Tree,Depth-First Search,Binary Tree	Medium
0688	Knight Probability in Chessboard	Dynamic Programming	Medium
0689	Maximum Sum of 3 Non-Overlapping Subarrays	Array,Dynamic Programming	Hard
0690	Employee Importance	Depth-First Search,Breadth-First Search,Hash Table	Easy
0691	Stickers to Spell Word	Bit Manipulation,Dynamic Programming,Backtracking,Bitmask	Hard
0692	Top K Frequent Words	Trie,Hash Table,String,Bucket Sort,Counting,Sorting,Heap (Priority Queue)	Medium
0693	Binary Number with Alternating Bits	Bit Manipulation	Easy
0694	Number of Distinct Islands	Depth-First Search,Breadth-First Search,Union Find,Hash Table,Hash Function	Medium	🔒
0695	Max Area of Island	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
0696	Count Binary Substrings	Two Pointers,String	Easy
0697	Degree of an Array	Array,Hash Table	Easy
0698	Partition to K Equal Sum Subsets	Bit Manipulation,Memoization,Array,Dynamic Programming,Backtracking,Bitmask	Medium
0700	Search in a Binary Search Tree	Tree,Binary Search Tree,Binary Tree	Easy
0701	Insert into a Binary Search Tree	Tree,Binary Search Tree,Binary Tree	Medium
0702	Search in a Sorted Array of Unknown Size	Array,Binary Search,Interactive	Medium	🔒
0703	Kth Largest Element in a Stream	Tree,Design,Binary Search Tree,Binary Tree,Data Stream,Heap (Priority Queue)	Easy
0704	Binary Search	Array,Binary Search	Easy
0710	Random Pick with Blacklist	Hash Table,Math,Binary Search,Sorting,Randomized	Hard
0712	Minimum ASCII Delete Sum for Two Strings	String,Dynamic Programming	Medium
0720	Longest Word in Dictionary	Trie,Array,Hash Table,String,Sorting	Easy
0749	Contain Virus	Depth-First Search,Breadth-First Search,Array,Matrix,Simulation	Hard
0750	Number Of Corner Rectangles	Array,Math,Dynamic Programming,Matrix	Medium	🔒
0751	IP to CIDR	Bit Manipulation,String	Medium	🔒
0752	Open the Lock	Breadth-First Search,Array,Hash Table,String	Medium
0753	Cracking the Safe	Depth-First Search,Graph,Eulerian Circuit	Hard
0754	Reach a Number	Math,Binary Search	Medium
0755	Pour Water	Array,Simulation	Medium	🔒
0756	Pyramid Transition Matrix	Bit Manipulation,Depth-First Search,Breadth-First Search	Medium
0757	Set Intersection Size At Least Two	Greedy,Array,Sorting	Hard
0766	Toeplitz Matrix	Array,Matrix	Easy
0767	Reorganize String	Greedy,Hash Table,String,Counting,Sorting,Heap (Priority Queue)	Medium
0768	Max Chunks To Make Sorted II	Stack,Greedy,Array,Sorting,Monotonic Stack	Hard
0769	Max Chunks To Make Sorted	Stack,Greedy,Array,Sorting,Monotonic Stack	Medium
0770	Basic Calculator IV	Stack,Recursion,Hash Table,Math,String	Hard
0771	Jewels and Stones	Hash Table,String	Easy
0772	Basic Calculator III	Stack,Recursion,Math,String	Hard	🔒
0773	Sliding Puzzle	Breadth-First Search,Array,Matrix	Hard
0774	Minimize Max Distance to Gas Station	Array,Binary Search	Hard	🔒
0775	Global and Local Inversions	Array,Math	Medium
0776	Split BST	Tree,Binary Search Tree,Recursion,Binary Tree	Medium	🔒
0777	Swap Adjacent in LR String	Two Pointers,String	Medium
0778	Swim in Rising Water	Depth-First Search,Breadth-First Search,Union Find,Array,Binary Search,Matrix,Heap (Priority Queue)	Hard
0779	K-th Symbol in Grammar	Bit Manipulation,Recursion,Math	Medium
0780	Reaching Points	Math	Hard
0781	Rabbits in Forest	Greedy,Hash Table,Math	Medium
0782	Transform to Chessboard	Bit Manipulation,Array,Math,Matrix	Hard
0783	Minimum Distance Between BST Nodes	Tree,Depth-First Search,Breadth-First Search,Binary Search Tree,Binary Tree	Easy
0784	Letter Case Permutation	Bit Manipulation,String,Backtracking	Medium
0785	Is Graph Bipartite	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0786	K-th Smallest Prime Fraction	Array,Binary Search,Heap (Priority Queue)	Hard
0787	Cheapest Flights Within K Stops	Depth-First Search,Breadth-First Search,Graph,Dynamic Programming,Shortest Path,Heap (Priority Queue)	Medium
0788	Rotated Digits	Math,Dynamic Programming	Medium
0789	Escape The Ghosts	Array,Math	Medium
0790	Domino and Tromino Tiling	Dynamic Programming	Medium
0791	Custom Sort String	Hash Table,String,Sorting	Medium
0792	Number of Matching Subsequences	Trie,Hash Table,String,Sorting	Medium
0793	Preimage Size of Factorial Zeroes Function	Math,Binary Search	Hard
0815	Bus Routes	Breadth-First Search,Array,Hash Table	Hard
0836	Rectangle Overlap	Geometry,Math	Easy
0844	Backspace String Compare	Stack,Two Pointers,String,Simulation	Easy
0861	Score After Flipping Matrix	Greedy,Bit Manipulation,Array,Matrix	Medium
0862	Shortest Subarray with Sum at Least K	Queue,Array,Binary Search,Prefix Sum,Sliding Window,Monotonic Queue,Heap (Priority Queue)	Hard
0863	All Nodes Distance K in Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0865	Smallest Subtree with all the Deepest Nodes	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium
0869	Reordered Power of 2	Math,Counting,Enumeration,Sorting	Medium
0870	Advantage Shuffle	Greedy,Array,Sorting	Medium
0871	Minimum Number of Refueling Stops	Greedy,Array,Dynamic Programming,Heap (Priority Queue)	Hard
0872	Leaf-Similar Trees	Tree,Depth-First Search,Binary Tree	Easy
0873	Length of Longest Fibonacci Subsequence	Array,Hash Table,Dynamic Programming	Medium
0874	Walking Robot Simulation	Array,Simulation	Medium
0875	Koko Eating Bananas	Array,Binary Search	Medium
0876	Middle of the Linked List	Linked List,Two Pointers	Easy
0877	Stone Game	Array,Math,Dynamic Programming,Game Theory	Medium
0878	Nth Magical Number	Math,Binary Search	Hard
0879	Profitable Schemes	Array,Dynamic Programming	Hard
0880	Decoded String at Index	Stack,String	Medium
0904	Fruit Into Baskets	Array,Hash Table,Sliding Window	Medium
0905	Sort Array By Parity	Array,Two Pointers,Sorting	Easy
0906	Super Palindromes	Math,Enumeration	Hard
0907	Sum of Subarray Minimums	Stack,Array,Dynamic Programming,Monotonic Stack	Medium
0908	Smallest Range I	Array,Math	Easy
0909	Snakes and Ladders	Breadth-First Search,Array,Matrix	Medium
0910	Smallest Range II	Greedy,Array,Math,Sorting	Medium
0911	Online Election	Design,Array,Hash Table,Binary Search	Medium
0912	Sort an Array	Array,Divide and Conquer,Bucket Sort,Counting Sort,Radix Sort,Sorting,Heap (Priority Queue),Merge Sort	Medium
0913	Cat and Mouse	Breadth-First Search,Graph,Memoization,Math,Dynamic Programming,Game Theory	Hard
0914	X of a Kind in a Deck of Cards	Array,Hash Table,Math,Counting,Number Theory	Easy
0915	Partition Array into Disjoint Intervals	Array	Medium
0916	Word Subsets	Array,Hash Table,String	Medium
0917	Reverse Only Letters	Two Pointers,String	Easy
0918	Maximum Sum Circular Subarray	Queue,Array,Divide and Conquer,Dynamic Programming,Monotonic Queue	Medium
0919	Complete Binary Tree Inserter	Tree,Breadth-First Search,Design,Binary Tree	Medium
0920	Number of Music Playlists	Math,Dynamic Programming,Combinatorics	Hard
0921	Minimum Add to Make Parentheses Valid	Stack,Greedy,String	Medium
0922	Sort Array By Parity II	Array,Two Pointers,Sorting	Easy
0923	3Sum With Multiplicity	Array,Hash Table,Two Pointers,Counting,Sorting	Medium
0924	Minimize Malware Spread	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Hard
0925	Long Pressed Name	Two Pointers,String	Easy
0926	Flip String to Monotone Increasing	String,Dynamic Programming	Medium
0927	Three Equal Parts	Array,Math	Hard
0928	Minimize Malware Spread II	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Hard
0929	Unique Email Addresses	Array,Hash Table,String	Easy
0930	Binary Subarrays With Sum	Array,Hash Table,Prefix Sum,Sliding Window	Medium
0932	Beautiful Array	Array,Math,Divide and Conquer	Medium
0943	Find the Shortest Superstring	Bit Manipulation,Array,String,Dynamic Programming,Bitmask	Hard
0944	Delete Columns to Make Sorted	Array,String	Easy
0945	Minimum Increment to Make Array Unique	Greedy,Array,Counting,Sorting	Medium
0946	Validate Stack Sequences	Stack,Array,Simulation	Medium
0947	Most Stones Removed with Same Row or Column	Depth-First Search,Union Find,Graph	Medium
0948	Bag of Tokens	Greedy,Array,Two Pointers,Sorting	Medium
0949	Largest Time for Given Digits	String,Enumeration	Medium
0950	Reveal Cards In Increasing Order	Queue,Array,Sorting,Simulation	Medium
0951	Flip Equivalent Binary Trees	Tree,Depth-First Search,Binary Tree	Medium
0952	Largest Component Size by Common Factor	Union Find,Array,Math	Hard
0953	Verifying an Alien Dictionary	Array,Hash Table,String	Easy
0954	Array of Doubled Pairs	Greedy,Array,Hash Table,Sorting	Medium
0955	Delete Columns to Make Sorted II	Greedy,Array,String	Medium
0956	Tallest Billboard	Array,Dynamic Programming	Hard
0957	Prison Cells After N Days	Bit Manipulation,Array,Hash Table,Math	Medium
0958	Check Completeness of a Binary Tree	Tree,Breadth-First Search,Binary Tree	Medium
0959	Regions Cut By Slashes	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0960	Delete Columns to Make Sorted III	Array,String,Dynamic Programming	Hard
0961	N-Repeated Element in Size 2N Array	Array,Hash Table	Easy
0962	Maximum Width Ramp	Stack,Array,Monotonic Stack	Medium
0963	Minimum Area Rectangle II	Geometry,Array,Math	Medium
0964	Least Operators to Express Number	Math,Dynamic Programming	Hard
0965	Univalued Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0966	Vowel Spellchecker	Array,Hash Table,String	Medium
0967	Numbers With Same Consecutive Differences	Breadth-First Search,Backtracking	Medium
0968	Binary Tree Cameras	Tree,Depth-First Search,Dynamic Programming,Binary Tree	Hard
0969	Pancake Sorting	Greedy,Array,Two Pointers,Sorting	Medium
0970	Powerful Integers	Hash Table,Math	Medium
0971	Flip Binary Tree To Match Preorder Traversal	Tree,Depth-First Search,Binary Tree	Medium
0972	Equal Rational Numbers	Math,String	Hard
0973	K Closest Points to Origin	Geometry,Array,Math,Divide and Conquer,Quickselect,Sorting,Heap (Priority Queue)	Medium
0974	Subarray Sums Divisible by K	Array,Hash Table,Prefix Sum	Medium
0975	Odd Even Jump	Stack,Array,Dynamic Programming,Ordered Set,Monotonic Stack	Hard
0976	Largest Perimeter Triangle	Greedy,Array,Math,Sorting	Easy
0977	Squares of a Sorted Array	Array,Two Pointers,Sorting	Easy
0978	Longest Turbulent Subarray	Array,Dynamic Programming,Sliding Window	Medium
0979	Distribute Coins in Binary Tree	Tree,Depth-First Search,Binary Tree	Medium
0981	Time Based Key-Value Store	Design,Hash Table,String,Binary Search	Medium
0990	Satisfiability of Equality Equations	Union Find,Graph,Array,String	Medium
0991	Broken Calculator	Greedy,Math	Medium
0992	Subarrays with K Different Integers	Array,Hash Table,Counting,Sliding Window	Hard
0993	Cousins in Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0994	Rotting Oranges	Breadth-First Search,Array,Matrix	Medium
0995	Minimum Number of K Consecutive Bit Flips	Bit Manipulation,Array,Prefix Sum,Sliding Window	Hard
0996	Number of Squareful Arrays	Bit Manipulation,Array,Math,Dynamic Programming,Backtracking,Bitmask	Hard
0997	Find the Town Judge	Graph,Array,Hash Table	Easy
0998	Maximum Binary Tree II	Tree,Binary Tree	Medium
0999	Available Captures for Rook	Array,Matrix,Simulation	Easy
1000	Minimum Cost to Merge Stones	Array,Dynamic Programming	Hard
1001	Grid Illumination	Array,Hash Table	Hard
1002	Find Common Characters	Array,Hash Table,String	Easy
1003	Check If Word Is Valid After Substitutions	Stack,String	Medium
1004	Max Consecutive Ones III	Array,Binary Search,Prefix Sum,Sliding Window	Medium
1005	Maximize Sum Of Array After K Negations	Greedy,Array,Sorting	Easy
1006	Clumsy Factorial	Stack,Math,Simulation	Medium
1007	Minimum Domino Rotations For Equal Row	Greedy,Array	Medium
1008	Construct Binary Search Tree from Preorder Traversal	Stack,Tree,Binary Search Tree,Array,Binary Tree,Monotonic Stack	Medium
1009	Complement of Base 10 Integer	Bit Manipulation	Easy
1010	Pairs of Songs With Total Durations Divisible by 60	Array,Hash Table,Counting	Medium
1011	Capacity To Ship Packages Within D Days	Greedy,Array,Binary Search	Medium
1012	Numbers With Repeated Digits	Math,Dynamic Programming	Hard
1013	Partition Array Into Three Parts With Equal Sum	Greedy,Array	Easy
1014	Best Sightseeing Pair	Array,Dynamic Programming	Medium
1015	Smallest Integer Divisible by K	Hash Table,Math	Medium
1016	Binary String With Substrings Representing 1 To N	String	Medium
1017	Convert to Base -2	Math	Medium
1018	Binary Prefix Divisible By 5	Array	Easy
1025	Divisor Game	Brainteaser,Math,Dynamic Programming,Game Theory	Easy
1026	Maximum Difference Between Node and Ancestor	Tree,Depth-First Search,Binary Tree	Medium
1027	Longest Arithmetic Subsequence	Array,Hash Table,Binary Search,Dynamic Programming	Medium
1028	Recover a Tree From Preorder Traversal	Tree,Depth-First Search,String,Binary Tree	Hard
1029	Two City Scheduling	Greedy,Array,Sorting	Medium
1030	Matrix Cells in Distance Order	Geometry,Array,Math,Matrix,Sorting	Easy
1031	Maximum Sum of Two Non-Overlapping Subarrays	Array,Dynamic Programming,Sliding Window	Medium
1032	Stream of Characters	Design,Trie,Array,String,Data Stream	Hard
1033	Moving Stones Until Consecutive	Brainteaser,Math	Medium
1034	Coloring A Border	Depth-First Search,Breadth-First Search,Array,Matrix	Medium
1035	Uncrossed Lines	Array,Dynamic Programming	Medium
1036	Escape a Large Maze	Depth-First Search,Breadth-First Search,Array,Hash Table	Hard
1037	Valid Boomerang	Geometry,Math	Easy
1038	Binary Search Tree to Greater Sum Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
1039	Minimum Score Triangulation of Polygon	Array,Dynamic Programming	Medium
1040	Moving Stones Until Consecutive II	Array,Math,Two Pointers,Sorting	Medium
1041	Robot Bounded In Circle	Math,String,Simulation	Medium
1042	Flower Planting With No Adjacent	Depth-First Search,Breadth-First Search,Graph	Medium
1043	Partition Array for Maximum Sum	Array,Dynamic Programming	Medium
1044	Longest Duplicate Substring	String,Binary Search,Suffix Array,Sliding Window,Hash Function,Rolling Hash	Hard
1054	Distant Barcodes	Greedy,Array,Hash Table,Counting,Sorting,Heap (Priority Queue)	Medium
1055	Shortest Way to Form String	Greedy,String,Dynamic Programming	Medium	🔒
1056	Confusing Number	Math	Easy	🔒
1057	Campus Bikes	Greedy,Array,Sorting	Medium	🔒
1058	Minimize Rounding Error to Meet Target	Greedy,Array,Math,String	Medium	🔒
1060	Missing Element in Sorted Array	Array,Binary Search	Medium	🔒
1061	Lexicographically Smallest Equivalent String	Union Find,String	Medium	🔒
1062	Longest Repeating Substring	String,Binary Search,Dynamic Programming,Suffix Array,Hash Function,Rolling Hash	Medium	🔒
1063	Number of Valid Subarrays	Stack,Array,Monotonic Stack	Hard	🔒
1064	Fixed Point	Array,Binary Search	Easy	🔒
1066	Campus Bikes II	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Medium	🔒
1067	Digit Count in Range	Math,Dynamic Programming	Hard	🔒
1068	Product Sales Analysis I	Database	Easy	🔒
1069	Product Sales Analysis II	Database	Easy	🔒
1070	Product Sales Analysis III	Database	Medium	🔒
1071	Greatest Common Divisor of Strings	Math,String	Easy
1072	Flip Columns For Maximum Number of Equal Rows	Array,Hash Table,Matrix	Medium
1073	Adding Two Negabinary Numbers	Array,Math	Medium
1074	Number of Submatrices That Sum to Target	Array,Hash Table,Matrix,Prefix Sum	Hard
1075	Project Employees I	Database	Easy	🔒
1076	Project Employees II	Database	Easy	🔒
1077	Project Employees III	Database	Medium	🔒
1078	Occurrences After Bigram	String	Easy
1079	Letter Tile Possibilities	String,Backtracking	Medium
1080	Insufficient Nodes in Root to Leaf Paths	Tree,Depth-First Search,Binary Tree	Medium
1081	Smallest Subsequence of Distinct Characters	Stack,Greedy,String,Monotonic Stack	Medium
1082	Sales Analysis I	Database	Easy	🔒
1083	Sales Analysis II	Database	Easy	🔒
1084	Sales Analysis III	Database	Easy	🔒
1089	Duplicate Zeros	Array,Two Pointers	Easy
1090	Largest Values From Labels	Greedy,Array,Hash Table,Counting,Sorting	Medium
1091	Shortest Path in Binary Matrix	Breadth-First Search,Array,Matrix	Medium
1092	Shortest Common Supersequence	String,Dynamic Programming	Hard
1099	Two Sum Less Than K	Array,Two Pointers,Binary Search,Sorting	Easy	🔒
1100	Find K-Length Substrings With No Repeated Characters	Hash Table,String,Sliding Window	Medium	🔒
1101	The Earliest Moment When Everyone Become Friends	Union Find,Array	Medium	🔒
1102	Path With Maximum Minimum Value	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix,Heap (Priority Queue)	Medium	🔒
1105	Filling Bookcase Shelves	Array,Dynamic Programming	Medium
1115	Print FooBar Alternately	Concurrency	Medium
1118	Number of Days in a Month	Math	Easy	🔒
1119	Remove Vowels from a String	String	Easy	🔒
1120	Maximum Average Subtree	Tree,Depth-First Search,Binary Tree	Medium	🔒
1121	Divide Array Into Increasing Sequences	Greedy,Array	Hard	🔒
1130	Minimum Cost Tree From Leaf Values	Stack,Greedy,Dynamic Programming,Monotonic Stack	Medium
1133	Largest Unique Number	Array,Hash Table,Sorting	Easy	🔒
1134	Armstrong Number	Math	Easy	🔒
1135	Connecting Cities With Minimum Cost	Union Find,Graph,Minimum Spanning Tree,Heap (Priority Queue)	Medium	🔒
1136	Parallel Courses	Graph,Topological Sort	Medium	🔒
1138	Alphabet Board Path	Hash Table,String	Medium
1139	Largest 1-Bordered Square	Array,Dynamic Programming,Matrix	Medium
1140	Stone Game II	Array,Math,Dynamic Programming,Game Theory	Medium
1141	User Activity for the Past 30 Days I	Database	Easy	🔒
1142	User Activity for the Past 30 Days II	Database	Easy	🔒
1143	Longest Common Subsequence	String,Dynamic Programming	Medium
1144	Decrease Elements To Make Array Zigzag	Greedy,Array	Medium
1145	Binary Tree Coloring Game	Tree,Depth-First Search,Binary Tree	Medium
1146	Snapshot Array	Design,Array,Hash Table,Binary Search	Medium
1147	Longest Chunked Palindrome Decomposition	Greedy,Two Pointers,String,Dynamic Programming,Hash Function,Rolling Hash	Hard
1148	Article Views I	Database	Easy	🔒
1149	Article Views II	Database	Medium	🔒
1150	Check If a Number Is Majority Element in a Sorted Array	Array,Binary Search	Easy	🔒
1151	Minimum Swaps to Group All 1's Together	Array,Sliding Window	Medium	🔒
1152	Analyze User Website Visit Pattern	Array,Hash Table,Sorting	Medium	🔒
1154	Day of the Year	Math,String	Easy
1155	Number of Dice Rolls With Target Sum	Dynamic Programming	Medium
1156	Swap For Longest Repeated Character Substring	String,Sliding Window	Medium
1157	Online Majority Element In Subarray	Design,Binary Indexed Tree,Segment Tree,Array,Binary Search	Hard
1158	Market Analysis I	Database	Medium	🔒
1159	Market Analysis II	Database	Hard	🔒
1160	Find Words That Can Be Formed by Characters	Array,Hash Table,String	Easy
1161	Maximum Level Sum of a Binary Tree	Tree,Breadth-First Search,Binary Tree	Medium
1162	As Far from Land as Possible	Breadth-First Search,Array,Dynamic Programming,Matrix	Medium
1164	Product Price at a Given Date	Database	Medium	🔒
1165	Single-Row Keyboard	Hash Table,String	Easy	🔒
1168	Optimize Water Distribution in a Village	Union Find,Graph,Minimum Spanning Tree	Hard	🔒
1169	Invalid Transactions	Array,Hash Table,String,Sorting	Medium
1170	Compare Strings by Frequency of the Smallest Character	Array,Hash Table,String,Binary Search,Sorting	Medium
1171	Remove Zero Sum Consecutive Nodes from Linked List	Hash Table,Linked List	Medium
1172	Dinner Plate Stacks	Stack,Design,Hash Table,Heap (Priority Queue)	Hard
1179	Reformat Department Table	Database	Easy
1183	Maximum Number of Ones	Greedy,Heap (Priority Queue)	Hard	🔒
1193	Monthly Transactions I	Database	Medium	🔒
1194	Tournament Winners	Database	Hard	🔒
1195	Fizz Buzz Multithreaded	Concurrency	Medium
1196	How Many Apples Can You Put into the Basket	Greedy,Array,Sorting	Easy	🔒
1197	Minimum Knight Moves	Breadth-First Search	Medium	🔒
1198	Find Smallest Common Element in All Rows	Array,Hash Table,Binary Search,Counting,Matrix	Medium	🔒
1199	Minimum Time to Build Blocks	Greedy,Math,Heap (Priority Queue)	Hard	🔒
1200	Minimum Absolute Difference	Array,Sorting	Easy
1201	Ugly Number III	Math,Binary Search,Number Theory	Medium
1202	Smallest String With Swaps	Depth-First Search,Breadth-First Search,Union Find,Hash Table,String	Medium
1203	Sort Items by Groups Respecting Dependencies	Depth-First Search,Breadth-First Search,Graph,Topological Sort	Hard
1204	Last Person to Fit in the Bus	Database	Medium	🔒
1205	Monthly Transactions II	Database	Medium	🔒
1206	Design Skiplist	Design,Linked List	Hard
1207	Unique Number of Occurrences	Array,Hash Table	Easy
1208	Get Equal Substrings Within Budget	String,Binary Search,Prefix Sum,Sliding Window	Medium
1209	Remove All Adjacent Duplicates in String II	Stack,String	Medium
1210	Minimum Moves to Reach Target with Rotations	Breadth-First Search,Array,Matrix	Hard
1213	Intersection of Three Sorted Arrays	Array,Hash Table,Binary Search,Counting	Easy	🔒
1214	Two Sum BSTs	Stack,Tree,Depth-First Search,Binary Search Tree,Two Pointers,Binary Search,Binary Tree	Medium	🔒
1215	Stepping Numbers	Breadth-First Search,Backtracking	Medium	🔒
1217	Minimum Cost to Move Chips to The Same Position	Greedy,Array,Math	Easy
1218	Longest Arithmetic Subsequence of Given Difference	Array,Hash Table,Dynamic Programming	Medium
1219	Path with Maximum Gold	Array,Backtracking,Matrix	Medium
1220	Count Vowels Permutation	Dynamic Programming	Hard
1227	Airplane Seat Assignment Probability	Brainteaser,Math,Dynamic Programming,Probability and Statistics	Medium
1228	Missing Number In Arithmetic Progression	Array,Math	Easy	🔒
1229	Meeting Scheduler	Array,Two Pointers,Sorting	Medium	🔒
1230	Toss Strange Coins	Math,Dynamic Programming,Probability and Statistics	Medium	🔒
1234	Replace the Substring for Balanced String	String,Sliding Window	Medium
1236	Web Crawler	Depth-First Search,Breadth-First Search,String,Interactive	Medium	🔒
1241	Number of Comments per Post	Database	Easy	🔒
1242	Web Crawler Multithreaded	Depth-First Search,Breadth-First Search,Concurrency	Medium	🔒
1244	Design A Leaderboard	Design,Hash Table,Sorting	Medium	🔒
1247	Minimum Swaps to Make Strings Equal	Greedy,Math,String	Medium
1248	Count Number of Nice Subarrays	Array,Hash Table,Math,Sliding Window	Medium
1249	Minimum Remove to Make Valid Parentheses	Stack,String	Medium
1250	Check If It Is a Good Array	Array,Math,Number Theory	Hard
1251	Average Selling Price	Database	Easy	🔒
1252	Cells with Odd Values in a Matrix	Array,Math,Simulation	Easy
1253	Reconstruct a 2-Row Binary Matrix	Greedy,Array,Matrix	Medium
1254	Number of Closed Islands	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
1255	Maximum Score Words Formed by Letters	Bit Manipulation,Array,String,Dynamic Programming,Backtracking,Bitmask	Hard
1260	Shift 2D Grid	Array,Matrix,Simulation	Easy
1261	Find Elements in a Contaminated Binary Tree	Tree,Depth-First Search,Breadth-First Search,Design,Binary Tree	Medium
1262	Greatest Sum Divisible by Three	Greedy,Array,Dynamic Programming	Medium
1263	Minimum Moves to Move a Box to Their Target Location	Breadth-First Search,Array,Matrix,Heap (Priority Queue)	Hard
1264	Page Recommendations	Database	Medium	🔒
1265	Print Immutable Linked List in Reverse	Stack,Recursion,Linked List,Two Pointers	Medium	🔒
1266	Minimum Time Visiting All Points	Geometry,Array,Math	Easy
1267	Count Servers that Communicate	Depth-First Search,Breadth-First Search,Union Find,Array,Counting,Matrix	Medium
1268	Search Suggestions System	Trie,Array,String	Medium
1269	Number of Ways to Stay in the Same Place After Some Steps	Dynamic Programming	Hard
1270	All People Report to the Given Manager	Database	Medium	🔒
1275	Find Winner on a Tic Tac Toe Game	Array,Hash Table,Matrix,Simulation	Easy
1276	Number of Burgers with No Waste of Ingredients	Math	Medium
1277	Count Square Submatrices with All Ones	Array,Dynamic Programming,Matrix	Medium
1278	Palindrome Partitioning III	String,Dynamic Programming	Hard
1293	Shortest Path in a Grid with Obstacles Elimination	Breadth-First Search,Array,Matrix	Hard
1294	Weather Type in Each Country	Database	Easy	🔒
1297	Maximum Number of Occurrences of a Substring	Hash Table,String,Sliding Window	Medium
1298	Maximum Candies You Can Get from Boxes	Breadth-First Search,Array	Hard
1302	Deepest Leaves Sum	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1303	Find the Team Size	Database	Easy	🔒
1304	Find N Unique Integers Sum up to Zero	Array,Math	Easy
1305	All Elements in Two Binary Search Trees	Tree,Depth-First Search,Binary Search Tree,Binary Tree,Sorting	Medium
1306	Jump Game III	Depth-First Search,Breadth-First Search,Array	Medium
1307	Verbal Arithmetic Puzzle	Array,Math,String,Backtracking	Hard
1308	Running Total for Different Genders	Database	Medium	🔒
1309	Decrypt String from Alphabet to Integer Mapping	String	Easy
1310	XOR Queries of a Subarray	Bit Manipulation,Array,Prefix Sum	Medium
1311	Get Watched Videos by Your Friends	Breadth-First Search,Array,Hash Table,Sorting	Medium
1312	Minimum Insertion Steps to Make a String Palindrome	String,Dynamic Programming	Hard
1313	Decompress Run-Length Encoded List	Array	Easy
1314	Matrix Block Sum	Array,Matrix,Prefix Sum	Medium
1315	Sum of Nodes with Even-Valued Grandparent	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1316	Distinct Echo Substrings	Trie,String,Dynamic Programming,Sliding Window,Hash Function,Rolling Hash	Hard
1317	Convert Integer to the Sum of Two No-Zero Integers	Math	Easy
1318	Minimum Flips to Make a OR b Equal to c	Bit Manipulation	Medium
1319	Number of Operations to Make Network Connected	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
1320	Minimum Distance to Type a Word Using Two Fingers	String,Dynamic Programming	Hard
1321	Restaurant Growth	Database	Medium	🔒
1322	Ads Performance	Database	Easy	🔒
1323	Maximum 69 Number	Greedy,Math	Easy
1324	Print Words Vertically	Array,String,Simulation	Medium
1325	Delete Leaves With a Given Value	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium
1326	Minimum Number of Taps to Open to Water a Garden	Greedy,Array,Dynamic Programming	Hard
1327	List the Products Ordered in a Period	Database	Easy	🔒
1328	Break a Palindrome	Greedy,String	Medium
1329	Sort the Matrix Diagonally	Array,Matrix,Sorting	Medium
1330	Reverse Subarray To Maximize Array Value	Greedy,Array,Math	Hard
1331	Rank Transform of an Array	Array,Hash Table,Sorting	Easy
1332	Remove Palindromic Subsequences	Two Pointers,String	Easy
1333	Filter Restaurants by Vegan-Friendly, Price and Distance	Array,Sorting	Medium
1334	Find the City With the Smallest Number of Neighbors at a Threshold Distance	Graph,Dynamic Programming,Shortest Path	Medium
1335	Minimum Difficulty of a Job Schedule	Array,Dynamic Programming	Hard
1337	The K Weakest Rows in a Matrix	Array,Binary Search,Matrix,Sorting,Heap (Priority Queue)	Easy
1341	Movie Rating	Database	Medium	🔒
1342	Number of Steps to Reduce a Number to Zero	Bit Manipulation,Math	Easy
1343	Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold	Array,Sliding Window	Medium
1344	Angle Between Hands of a Clock	Math	Medium
1345	Jump Game IV	Breadth-First Search,Array,Hash Table	Hard
1346	Check If N and Its Double Exist	Array,Hash Table,Two Pointers,Binary Search,Sorting	Easy
1350	Students With Invalid Departments	Database	Easy	🔒
1351	Count Negative Numbers in a Sorted Matrix	Array,Binary Search,Matrix	Easy
1352	Product of the Last K Numbers	Design,Queue,Array,Math,Data Stream	Medium
1353	Maximum Number of Events That Can Be Attended	Greedy,Array,Heap (Priority Queue)	Medium
1354	Construct Target Array With Multiple Sums	Array,Heap (Priority Queue)	Hard
1355	Activity Participants	Database	Medium	🔒
1356	Sort Integers by The Number of 1 Bits	Bit Manipulation,Array,Counting,Sorting	Easy
1357	Apply Discount Every n Orders	Design,Array,Hash Table	Medium
1358	Number of Substrings Containing All Three Characters	Hash Table,String,Sliding Window	Medium
1359	Count All Valid Pickup and Delivery Options	Math,Dynamic Programming,Combinatorics	Hard
1360	Number of Days Between Two Dates	Math,String	Easy
1361	Validate Binary Tree Nodes	Tree,Depth-First Search,Breadth-First Search,Union Find,Graph,Binary Tree	Medium
1362	Closest Divisors	Math	Medium
1363	Largest Multiple of Three	Greedy,Array,Dynamic Programming	Hard
1364	Number of Trusted Contacts of a Customer	Database	Medium	🔒
1365	How Many Numbers Are Smaller Than the Current Number	Array,Hash Table,Counting,Sorting	Easy
1366	Rank Teams by Votes	Array,Hash Table,String,Counting,Sorting	Medium
1367	Linked List in Binary Tree	Tree,Depth-First Search,Breadth-First Search,Linked List,Binary Tree	Medium
1368	Minimum Cost to Make at Least One Valid Path in a Grid	Breadth-First Search,Graph,Array,Matrix,Shortest Path,Heap (Priority Queue)	Hard
1369	Get the Second Most Recent Activity	Database	Hard	🔒
1374	Generate a String With Characters That Have Odd Counts	String	Easy
1375	Bulb Switcher III	Array	Medium
1376	Time Needed to Inform All Employees	Tree,Depth-First Search,Breadth-First Search	Medium
1377	Frog Position After T Seconds	Tree,Depth-First Search,Breadth-First Search,Graph	Hard
1378	Replace Employee ID With The Unique Identifier	Database	Easy	🔒
1379	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1380	Lucky Numbers in a Matrix	Array,Matrix	Easy
1381	Design a Stack With Increment Operation	Stack,Design,Array	Medium
1383	Maximum Performance of a Team	Greedy,Array,Sorting,Heap (Priority Queue)	Hard
1385	Find the Distance Value Between Two Arrays	Array,Two Pointers,Binary Search,Sorting	Easy
1386	Cinema Seat Allocation	Greedy,Bit Manipulation,Array,Hash Table	Medium
1387	Sort Integers by The Power Value	Memoization,Dynamic Programming,Sorting	Medium
1388	Pizza With 3n Slices	Greedy,Array,Dynamic Programming,Heap (Priority Queue)	Hard
1389	Create Target Array in the Given Order	Array,Simulation	Easy
1391	Check if There is a Valid Path in a Grid	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
1392	Longest Happy Prefix	String,String Matching,Hash Function,Rolling Hash	Hard
1394	Find Lucky Integer in an Array	Array,Hash Table,Counting	Easy
1395	Count Number of Teams	Binary Indexed Tree,Array,Dynamic Programming	Medium
1396	Design Underground System	Design,Hash Table,String	Medium
1397	Find All Good Strings	String,Dynamic Programming,String Matching	Hard
1398	Customers Who Bought Products A and B but Not C	Database	Medium	🔒
1399	Count Largest Group	Hash Table,Math	Easy
1400	Construct K Palindrome Strings	Greedy,Hash Table,String,Counting	Medium
1401	Circle and Rectangle Overlapping	Geometry,Math	Medium
1402	Reducing Dishes	Greedy,Array,Dynamic Programming,Sorting	Hard
1405	Longest Happy String	Greedy,String,Heap (Priority Queue)	Medium
1407	Top Travellers	Database	Easy	🔒
1409	Queries on a Permutation With Key	Binary Indexed Tree,Array,Simulation	Medium
1412	Find the Quiet Students in All Exams	Database	Hard	🔒
1413	Minimum Value to Get Positive Step by Step Sum	Array,Prefix Sum	Easy
1417	Reformat The String	String	Easy
1418	Display Table of Food Orders in a Restaurant	Array,Hash Table,String,Ordered Set,Sorting	Medium
1419	Minimum Number of Frogs Croaking	String,Counting	Medium
1420	Build Array Where You Can Find The Maximum Exactly K Comparisons	Dynamic Programming	Hard
1421	NPV Queries	Database	Medium	🔒
1422	Maximum Score After Splitting a String	String	Easy
1423	Maximum Points You Can Obtain from Cards	Array,Prefix Sum,Sliding Window	Medium
1424	Diagonal Traverse II	Array,Sorting,Heap (Priority Queue)	Medium
1425	Constrained Subsequence Sum	Queue,Array,Dynamic Programming,Sliding Window,Monotonic Queue,Heap (Priority Queue)	Hard
1426	Counting Elements	Array,Hash Table	Easy	🔒
1428	Leftmost Column with at Least a One	Array,Binary Search,Interactive,Matrix	Medium	🔒
1429	First Unique Number	Design,Queue,Array,Hash Table,Data Stream	Medium	🔒
1430	Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium	🔒
1431	Kids With the Greatest Number of Candies	Array	Easy
1432	Max Difference You Can Get From Changing an Integer	Greedy,Math	Medium
1433	Check If a String Can Break Another String	Greedy,String,Sorting	Medium
1434	Number of Ways to Wear Different Hats to Each Other	Bit Manipulation,Array,Dynamic Programming,Bitmask	Hard
1435	Create a Session Bar Chart	Database	Easy	🔒
1436	Destination City	Hash Table,String	Easy
1437	Check If All 1's Are at Least Length K Places Away	Array	Easy
1438	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	Queue,Array,Ordered Set,Sliding Window,Monotonic Queue,Heap (Priority Queue)	Medium
1439	Find the Kth Smallest Sum of a Matrix With Sorted Rows	Array,Binary Search,Matrix,Heap (Priority Queue)	Hard
1440	Evaluate Boolean Expression	Database	Medium	🔒
1441	Build an Array With Stack Operations	Stack,Array,Simulation	Easy
1442	Count Triplets That Can Form Two Arrays of Equal XOR	Bit Manipulation,Array,Hash Table,Math,Prefix Sum	Medium
1443	Minimum Time to Collect All Apples in a Tree	Tree,Depth-First Search,Breadth-First Search,Hash Table	Medium
1444	Number of Ways of Cutting a Pizza	Memoization,Array,Dynamic Programming,Matrix	Hard
1445	Apples & Oranges	Database	Medium	🔒
1446	Consecutive Characters	String	Easy
1447	Simplified Fractions	Math	Medium
1448	Count Good Nodes in Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1449	Form Largest Integer With Digits That Add up to Target	Array,Dynamic Programming	Hard
1450	Number of Students Doing Homework at a Given Time	Array	Easy
1451	Rearrange Words in a Sentence	String,Sorting	Medium
1452	People Whose List of Favorite Companies Is Not a Subset of Another List	Array,Hash Table,String	Medium
1453	Maximum Number of Darts Inside of a Circular Dartboard	Geometry,Array,Math	Hard
1454	Active Users	Database	Medium	🔒
1455	Check If a Word Occurs As a Prefix of Any Word in a Sentence	String,String Matching	Easy
1457	Pseudo-Palindromic Paths in a Binary Tree	Bit Manipulation,Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1459	Rectangles Area	Database	Medium	🔒
1460	Make Two Arrays Equal by Reversing Sub-arrays	Array,Hash Table,Sorting	Easy
1461	Check If a String Contains All Binary Codes of Size K	Bit Manipulation,Hash Table,String,Hash Function,Rolling Hash	Medium
1462	Course Schedule IV	Depth-First Search,Breadth-First Search,Graph,Topological Sort	Medium
1463	Cherry Pickup II	Array,Dynamic Programming,Matrix	Hard
1465	Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts	Greedy,Array,Sorting	Medium
1468	Calculate Salaries	Database	Medium	🔒
1469	Find All The Lonely Nodes	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy	🔒
1470	Shuffle the Array	Array	Easy
1471	The k Strongest Values in an Array	Array,Two Pointers,Sorting	Medium
1472	Design Browser History	Stack,Design,Array,Linked List,Data Stream,Doubly-Linked List	Medium
1473	Paint House III	Array,Dynamic Programming	Hard
1474	Delete N Nodes After M Nodes of a Linked List	Linked List	Easy	🔒
1479	Sales by Day of the Week	Database	Hard	🔒
1480	Running Sum of 1d Array	Array,Prefix Sum	Easy
1481	Least Number of Unique Integers after K Removals	Greedy,Array,Hash Table,Counting,Sorting	Medium
1482	Minimum Number of Days to Make m Bouquets	Array,Binary Search	Medium
1484	Group Sold Products By The Date	Database	Easy	🔒
1485	Clone Binary Tree With Random Pointer	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium	🔒
1486	XOR Operation in an Array	Bit Manipulation,Math	Easy
1487	Making File Names Unique	Array,Hash Table,String	Medium
1488	Avoid Flood in The City	Greedy,Array,Hash Table,Binary Search,Heap (Priority Queue)	Medium
1489	Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree	Union Find,Graph,Minimum Spanning Tree,Sorting,Strongly Connected Component	Hard
1491	Average Salary Excluding the Minimum and Maximum Salary	Array,Sorting	Easy
1492	The kth Factor of n	Math	Medium
1493	Longest Subarray of 1's After Deleting One Element	Math,Dynamic Programming,Sliding Window	Medium
1494	Parallel Courses II	Bit Manipulation,Graph,Dynamic Programming,Bitmask	Hard
1496	Path Crossing	Hash Table,String	Easy
1497	Check If Array Pairs Are Divisible by k	Array,Hash Table,Counting	Medium
1498	Number of Subsequences That Satisfy the Given Sum Condition	Array,Two Pointers,Binary Search,Sorting	Medium
1499	Max Value of Equation	Queue,Array,Sliding Window,Monotonic Queue,Heap (Priority Queue)	Hard
1502	Can Make Arithmetic Progression From Sequence	Array,Sorting	Easy
1503	Last Moment Before All Ants Fall Out of a Plank	Brainteaser,Array,Simulation	Medium
1504	Count Submatrices With All Ones	Stack,Array,Dynamic Programming,Matrix,Monotonic Stack	Medium
1505	Minimum Possible Integer After at Most K Adjacent Swaps On Digits	Greedy,Binary Indexed Tree,Segment Tree,String	Hard
1506	Find Root of N-Ary Tree	Bit Manipulation,Tree,Depth-First Search,Hash Table	Medium	🔒
1508	Range Sum of Sorted Subarray Sums	Array,Two Pointers,Binary Search,Sorting	Medium
1509	Minimum Difference Between Largest and Smallest Value in Three Moves	Greedy,Array,Sorting	Medium
1510	Stone Game IV	Math,Dynamic Programming,Game Theory	Hard
1511	Customer Order Frequency	Database	Easy	🔒
1514	Path with Maximum Probability	Graph,Shortest Path,Heap (Priority Queue)	Medium
1516	Move Sub-Tree of N-Ary Tree	Tree,Depth-First Search	Hard	🔒
1517	Find Users With Valid E-Mails	Database	Easy	🔒
1521	Find a Value of a Mysterious Function Closest to Target	Bit Manipulation,Segment Tree,Array,Binary Search	Hard
1522	Diameter of N-Ary Tree	Tree,Depth-First Search	Medium	🔒
1523	Count Odd Numbers in an Interval Range	Math	Easy
1524	Number of Sub-arrays With Odd Sum	Array,Math,Dynamic Programming,Prefix Sum	Medium
1525	Number of Good Ways to Split a String	Bit Manipulation,String,Dynamic Programming	Medium
1526	Minimum Number of Increments on Subarrays to Form a Target Array	Stack,Greedy,Array,Dynamic Programming,Monotonic Stack	Hard
1527	Patients With a Condition	Database	Easy	🔒
1528	Shuffle String	Array,String	Easy
1529	Bulb Switcher IV	Greedy,String	Medium
1530	Number of Good Leaf Nodes Pairs	Tree,Depth-First Search,Binary Tree	Medium
1532	The Most Recent Three Orders	Database	Medium	🔒
1533	Find the Index of the Large Integer	Array,Binary Search,Interactive	Medium	🔒
1534	Count Good Triplets	Array,Enumeration	Easy
1535	Find the Winner of an Array Game	Array,Simulation	Medium
1536	Minimum Swaps to Arrange a Binary Grid	Greedy,Array,Matrix	Medium
1537	Get the Maximum Score	Greedy,Array,Two Pointers,Dynamic Programming	Hard
1538	Guess the Majority in a Hidden Array	Array,Math,Interactive	Medium	🔒
1539	Kth Missing Positive Number	Array,Binary Search	Easy
1540	Can Convert String in K Moves	Hash Table,String	Medium
1541	Minimum Insertions to Balance a Parentheses String	Stack,Greedy,String	Medium
1542	Find Longest Awesome Substring	Bit Manipulation,Hash Table,String	Hard
1544	Make The String Great	Stack,String	Easy
1545	Find Kth Bit in Nth Binary String	Recursion,String	Medium
1546	Maximum Number of Non-Overlapping Subarrays With Sum Equals Target	Greedy,Array,Hash Table,Prefix Sum	Medium
1547	Minimum Cost to Cut a Stick	Array,Dynamic Programming	Hard
1551	Minimum Operations to Make Array Equal	Math	Medium
1552	Magnetic Force Between Two Balls	Array,Binary Search,Sorting	Medium
1553	Minimum Number of Days to Eat N Oranges	Memoization,Dynamic Programming	Hard
1554	Strings Differ by One Character	Hash Table,String,Hash Function,Rolling Hash	Medium	🔒
1555	Bank Account Summary	Database	Medium	🔒
1556	Thousand Separator	String	Easy
1557	Minimum Number of Vertices to Reach All Nodes	Graph	Medium
1558	Minimum Numbers of Function Calls to Make Target Array	Greedy,Array	Medium
1559	Detect Cycles in 2D Grid	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
1560	Most Visited Sector in a Circular Track	Array,Simulation	Easy
1561	Maximum Number of Coins You Can Get	Greedy,Array,Math,Game Theory,Sorting	Medium
1562	Find Latest Group of Size M	Array,Binary Search,Simulation	Medium
1564	Put Boxes Into the Warehouse I	Greedy,Array,Sorting	Medium	🔒
1565	Unique Orders and Customers Per Month	Database	Easy	🔒
1570	Dot Product of Two Sparse Vectors	Design,Array,Hash Table,Two Pointers	Medium	🔒
1571	Warehouse Manager	Database	Easy	🔒
1572	Matrix Diagonal Sum	Array,Matrix	Easy
1573	Number of Ways to Split a String	Math,String	Medium
1574	Shortest Subarray to be Removed to Make Array Sorted	Stack,Array,Two Pointers,Binary Search,Monotonic Stack	Medium
1575	Count All Possible Routes	Memoization,Array,Dynamic Programming	Hard
1576	Replace All 's to Avoid Consecutive Repeating Characters	String	Easy
1577	Number of Ways Where Square of Number Is Equal to Product of Two Numbers	Array,Hash Table,Math,Two Pointers	Medium
1578	Minimum Deletion Cost to Avoid Repeating Letters	Greedy,Array,String,Dynamic Programming	Medium
1579	Remove Max Number of Edges to Keep Graph Fully Traversable	Union Find,Graph	Hard
1580	Put Boxes Into the Warehouse II	Greedy,Array,Sorting	Medium	🔒
1581	Customer Who Visited but Did Not Make Any Transactions	Database	Easy	🔒
1582	Special Positions in a Binary Matrix	Array,Matrix	Easy
1583	Count Unhappy Friends	Array,Simulation	Medium
1584	Min Cost to Connect All Points	Union Find,Array,Minimum Spanning Tree	Medium
1585	Check If String Is Transformable With Substring Sort Operations	Greedy,String,Sorting	Hard
1586	Binary Search Tree Iterator II	Stack,Tree,Design,Binary Search Tree,Binary Tree,Iterator	Medium	🔒
1587	Bank Account Summary II	Database	Easy	🔒
1589	Maximum Sum Obtained of Any Permutation	Greedy,Array,Prefix Sum,Sorting	Medium
1590	Make Sum Divisible by P	Array,Hash Table,Prefix Sum	Medium
1591	Strange Printer II	Graph,Topological Sort,Array,Matrix	Hard
1592	Rearrange Spaces Between Words	String	Easy
1593	Split a String Into the Max Number of Unique Substrings	Hash Table,String,Backtracking	Medium
1594	Maximum Non Negative Product in a Matrix	Array,Dynamic Programming,Matrix	Medium
1595	Minimum Cost to Connect Two Groups of Points	Bit Manipulation,Array,Dynamic Programming,Bitmask,Matrix	Hard
1596	The Most Frequently Ordered Products for Each Customer	Database	Medium	🔒
1597	Build Binary Expression Tree From Infix Expression	Stack,Tree,String,Binary Tree	Hard	🔒
1598	Crawler Log Folder	Stack,Array,String	Easy
1599	Maximum Profit of Operating a Centennial Wheel	Array,Simulation	Medium
1600	Throne Inheritance	Tree,Depth-First Search,Design,Hash Table	Medium
1601	Maximum Number of Achievable Transfer Requests	Bit Manipulation,Enumeration	Hard
1602	Find Nearest Right Node in Binary Tree	Tree,Breadth-First Search,Binary Tree	Medium	🔒
1603	Design Parking System	Design,Counting,Simulation	Easy
1604	Alert Using Same Key-Card Three or More Times in a One Hour Period	Array,Hash Table,String,Sorting	Medium
1605	Find Valid Matrix Given Row and Column Sums	Greedy,Array,Matrix	Medium
1606	Find Servers That Handled Most Number of Requests	Greedy,Array,Ordered Set,Heap (Priority Queue)	Hard
1607	Sellers With No Sales	Database	Easy	🔒
1608	Special Array With X Elements Greater Than or Equal X	Array,Binary Search,Sorting	Easy
1609	Even Odd Tree	Tree,Breadth-First Search,Binary Tree	Medium
1610	Maximum Number of Visible Points	Geometry,Array,Math,Sorting,Sliding Window	Hard
1611	Minimum One Bit Operations to Make Integers Zero	Bit Manipulation,Memoization,Dynamic Programming	Hard
1612	Check If Two Expression Trees are Equivalent	Tree,Depth-First Search,Binary Tree	Medium	🔒
1613	Find the Missing IDs	Database	Medium	🔒
1614	Maximum Nesting Depth of the Parentheses	Stack,String	Easy
1615	Maximal Network Rank	Graph	Medium
1616	Split Two Strings to Make Palindrome	Greedy,Two Pointers,String	Medium
1617	Count Subtrees With Max Distance Between Cities	Bit Manipulation,Tree,Dynamic Programming,Bitmask,Enumeration	Hard
1618	Maximum Font to Fit a Sentence in a Screen	Array,String,Binary Search,Interactive	Medium	🔒
1620	Coordinate With Maximum Network Quality	Array,Enumeration	Medium
1621	Number of Sets of K Non-Overlapping Line Segments	Math,Dynamic Programming	Medium
1622	Fancy Sequence	Design,Segment Tree,Math	Hard
1623	All Valid Triplets That Can Represent a Country	Database	Easy	🔒
1624	Largest Substring Between Two Equal Characters	Hash Table,String	Easy
1625	Lexicographically Smallest String After Applying Operations	Breadth-First Search,String	Medium
1626	Best Team With No Conflicts	Array,Dynamic Programming,Sorting	Medium
1628	Design an Expression Tree With Evaluate Function	Stack,Tree,Design,Math,Binary Tree	Medium	🔒
1629	Slowest Key	Array,String	Easy
1630	Arithmetic Subarrays	Array,Sorting	Medium
1631	Path With Minimum Effort	Depth-First Search,Breadth-First Search,Union Find,Array,Binary Search,Matrix,Heap (Priority Queue)	Medium
1632	Rank Transform of a Matrix	Greedy,Union Find,Graph,Topological Sort,Array,Matrix	Hard
1633	Percentage of Users Attended a Contest	Database	Easy	🔒
1634	Add Two Polynomials Represented as Linked Lists	Linked List,Math,Two Pointers	Medium	🔒
1635	Hopper Company Queries I	Database	Hard	🔒
1636	Sort Array by Increasing Frequency	Array,Hash Table,Sorting	Easy
1637	Widest Vertical Area Between Two Points Containing No Points	Array,Sorting	Medium
1638	Count Substrings That Differ by One Character	Hash Table,String,Dynamic Programming	Medium
1639	Number of Ways to Form a Target String Given a Dictionary	Array,String,Dynamic Programming	Hard
1640	Check Array Formation Through Concatenation	Array,Hash Table	Easy
1641	Count Sorted Vowel Strings	Dynamic Programming	Medium
1642	Furthest Building You Can Reach	Greedy,Array,Heap (Priority Queue)	Medium
1644	Lowest Common Ancestor of a Binary Tree II	Tree,Depth-First Search,Binary Tree	Medium	🔒
1645	Hopper Company Queries II	Database	Hard	🔒
1646	Get Maximum in Generated Array	Array,Dynamic Programming,Simulation	Easy
1647	Minimum Deletions to Make Character Frequencies Unique	Greedy,String,Sorting	Medium
1648	Sell Diminishing-Valued Colored Balls	Greedy,Array,Math,Binary Search,Sorting,Heap (Priority Queue)	Medium
1649	Create Sorted Array through Instructions	Binary Indexed Tree,Segment Tree,Array,Binary Search,Divide and Conquer,Ordered Set,Merge Sort	Hard
1650	Lowest Common Ancestor of a Binary Tree III	Tree,Hash Table,Binary Tree	Medium	🔒
1651	Hopper Company Queries III	Database	Hard	🔒
1652	Defuse the Bomb	Array	Easy
1653	Minimum Deletions to Make String Balanced	Stack,String,Dynamic Programming	Medium
1654	Minimum Jumps to Reach Home	Breadth-First Search,Array,Dynamic Programming	Medium
1655	Distribute Repeating Integers	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Hard
1656	Design an Ordered Stream	Design,Array,Hash Table,Data Stream	Easy
1657	Determine if Two Strings Are Close	Hash Table,String,Sorting	Medium
1658	Minimum Operations to Reduce X to Zero	Array,Hash Table,Two Pointers,Binary Search,Prefix Sum	Medium
1659	Maximize Grid Happiness	Bit Manipulation,Memoization,Dynamic Programming,Bitmask	Hard
1660	Correct a Binary Tree	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium	🔒
1661	Average Time of Process per Machine	Database	Easy	🔒
1662	Check If Two String Arrays are Equivalent	Array,String	Easy
1663	Smallest String With A Given Numeric Value	Greedy,String	Medium
1664	Ways to Make a Fair Array	Array,Dynamic Programming	Medium
1665	Minimum Initial Energy to Finish Tasks	Greedy,Array,Sorting	Hard
1666	Change the Root of a Binary Tree	Tree,Depth-First Search,Binary Tree	Medium	🔒
1667	Fix Names in a Table	Database	Easy	🔒
1668	Maximum Repeating Substring	String,String Matching	Easy
1669	Merge In Between Linked Lists	Linked List	Medium
1670	Design Front Middle Back Queue	Design,Queue,Array,Linked List,Data Stream	Medium
1671	Minimum Number of Removals to Make Mountain Array	Greedy,Array,Binary Search,Dynamic Programming	Hard
1676	Lowest Common Ancestor of a Binary Tree IV	Tree,Depth-First Search,Binary Tree	Medium	🔒
1677	Product's Worth Over Invoices	Database	Easy	🔒
1678	Goal Parser Interpretation	String	Easy
1679	Max Number of K-Sum Pairs	Array,Hash Table,Two Pointers,Sorting	Medium
1680	Concatenation of Consecutive Binary Numbers	Bit Manipulation,Math,Simulation	Medium
1681	Minimum Incompatibility	Bit Manipulation,Array,Dynamic Programming,Bitmask	Hard
1682	Longest Palindromic Subsequence II	String,Dynamic Programming	Medium	🔒
1683	Invalid Tweets	Database	Easy	🔒
1688	Count of Matches in Tournament	Math,Simulation	Easy
1689	Partitioning Into Minimum Number Of Deci-Binary Numbers	Greedy,String	Medium
1690	Stone Game VII	Array,Math,Dynamic Programming,Game Theory	Medium
1691	Maximum Height by Stacking Cuboids	Array,Dynamic Programming,Sorting	Hard
1692	Count Ways to Distribute Candies	Dynamic Programming	Hard	🔒
1694	Reformat Phone Number	String	Easy
1695	Maximum Erasure Value	Array,Hash Table,Sliding Window	Medium
1696	Jump Game VI	Queue,Array,Dynamic Programming,Sliding Window,Monotonic Queue,Heap (Priority Queue)	Medium
1697	Checking Existence of Edge Length Limited Paths	Union Find,Graph,Array,Sorting	Hard
1700	Number of Students Unable to Eat Lunch	Stack,Queue,Array,Simulation	Easy
1701	Average Waiting Time	Array,Simulation	Medium
1702	Maximum Binary String After Change	Greedy,String	Medium
1703	Minimum Adjacent Swaps for K Consecutive Ones	Greedy,Array,Prefix Sum,Sliding Window	Hard
1704	Determine if String Halves Are Alike	String,Counting	Easy
1705	Maximum Number of Eaten Apples	Greedy,Array,Heap (Priority Queue)	Medium
1706	Where Will the Ball Fall	Depth-First Search,Array,Dynamic Programming,Matrix,Simulation	Medium
1707	Maximum XOR With an Element From Array	Bit Manipulation,Trie,Array	Hard
1709	Biggest Window Between Visits	Database	Medium	🔒
1710	Maximum Units on a Truck	Greedy,Array,Sorting	Easy
1711	Count Good Meals	Array,Hash Table	Medium
1712	Ways to Split Array Into Three Subarrays	Array,Two Pointers,Binary Search,Prefix Sum	Medium
1713	Minimum Operations to Make a Subsequence	Greedy,Array,Hash Table,Binary Search	Hard
1714	Sum Of Special Evenly-Spaced Elements In Array	Array,Dynamic Programming	Hard	🔒
1715	Count Apples and Oranges	Database	Medium	🔒
1716	Calculate Money in Leetcode Bank	Math	Easy
1717	Maximum Score From Removing Substrings	Stack,Greedy,String	Medium
1718	Construct the Lexicographically Largest Valid Sequence	Array,Backtracking	Medium
1719	Number Of Ways To Reconstruct A Tree	Tree,Graph,Topological Sort	Hard
1723	Find Minimum Time to Finish All Jobs	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Hard
1724	Checking Existence of Edge Length Limited Paths II	Union Find,Graph,Minimum Spanning Tree	Hard	🔒
1726	Tuple with Same Product	Array,Hash Table	Medium
1728	Cat and Mouse II	Breadth-First Search,Graph,Memoization,Math,Dynamic Programming,Game Theory	Hard
1729	Find Followers Count	Database	Easy	🔒
1731	The Number of Employees Which Report to Each Employee	Database	Easy	🔒
1732	Find the Highest Altitude	Array,Prefix Sum	Easy
1733	Minimum Number of People to Teach	Greedy,Array	Medium
1734	Decode XORed Permutation	Bit Manipulation,Array	Medium
1736	Latest Time by Replacing Hidden Digits	String	Easy
1737	Change Minimum Characters to Satisfy One of Three Conditions	Hash Table,String,Counting,Prefix Sum	Medium
1738	Find Kth Largest XOR Coordinate Value	Bit Manipulation,Array,Divide and Conquer,Matrix,Prefix Sum,Quickselect,Heap (Priority Queue)	Medium
1739	Building Boxes	Greedy,Math,Binary Search	Hard
1740	Find Distance in a Binary Tree	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium	🔒
1741	Find Total Time Spent by Each Employee	Database	Easy	🔒
1743	Restore the Array From Adjacent Pairs	Array,Hash Table	Medium
1744	Can You Eat Your Favorite Candy on Your Favorite Day	Array,Prefix Sum	Medium
1745	Palindrome Partitioning IV	String,Dynamic Programming	Hard
1746	Maximum Subarray Sum After One Operation	Array,Dynamic Programming	Medium	🔒
1747	Leetflex Banned Accounts	Database	Medium	🔒
1751	Maximum Number of Events That Can Be Attended II	Array,Binary Search,Dynamic Programming	Hard
1752	Check if Array Is Sorted and Rotated	Array	Easy
1753	Maximum Score From Removing Stones	Greedy,Math,Heap (Priority Queue)	Medium
1754	Largest Merge Of Two Strings	Greedy,Two Pointers,String	Medium
1755	Closest Subsequence Sum	Bit Manipulation,Array,Two Pointers,Dynamic Programming,Bitmask	Hard
1757	Recyclable and Low Fat Products	Database	Easy	🔒
1758	Minimum Changes To Make Alternating Binary String	String	Easy
1759	Count Number of Homogenous Substrings	Math,String	Medium
1760	Minimum Limit of Balls in a Bag	Array,Binary Search	Medium
1761	Minimum Degree of a Connected Trio in a Graph	Graph	Hard
1762	Buildings With an Ocean View	Stack,Array,Monotonic Stack	Medium	🔒
1763	Longest Nice Substring	Bit Manipulation,Hash Table,String,Sliding Window	Easy
1764	Form Array by Concatenating Subarrays of Another Array	Greedy,Array,String Matching	Medium
1765	Map of Highest Peak	Breadth-First Search,Array,Matrix	Medium
1766	Tree of Coprimes	Tree,Depth-First Search,Breadth-First Search,Math	Hard
1767	Find the Subtasks That Did Not Execute	Database	Hard	🔒
1768	Merge Strings Alternately	Two Pointers,String	Easy
1769	Minimum Number of Operations to Move All Balls to Each Box	Array,String	Medium
1770	Maximum Score from Performing Multiplication Operations	Array,Dynamic Programming	Medium
1771	Maximize Palindrome Length From Subsequences	String,Dynamic Programming	Hard
1772	Sort Features by Popularity	Array,Hash Table,String,Sorting	Medium	🔒
1773	Count Items Matching a Rule	Array,String	Easy
1774	Closest Dessert Cost	Array,Dynamic Programming,Backtracking	Medium
1775	Equal Sum Arrays With Minimum Number of Operations	Greedy,Array,Hash Table,Counting	Medium
1776	Car Fleet II	Stack,Array,Math,Monotonic Stack,Heap (Priority Queue)	Hard
1777	Product's Price for Each Store	Database	Easy	🔒
1778	Shortest Path in a Hidden Grid	Depth-First Search,Breadth-First Search,Graph,Interactive	Medium	🔒
1779	Find Nearest Point That Has the Same X or Y Coordinate	Array	Easy
1780	Check if Number is a Sum of Powers of Three	Math	Medium
1781	Sum of Beauty of All Substrings	Hash Table,String,Counting	Medium
1782	Count Pairs Of Nodes	Graph,Two Pointers,Binary Search	Hard
1783	Grand Slam Titles	Database	Medium	🔒
1784	Check if Binary String Has at Most One Segment of Ones	String	Easy
1785	Minimum Elements to Add to Form a Given Sum	Greedy,Array	Medium
1786	Number of Restricted Paths From First to Last Node	Graph,Topological Sort,Dynamic Programming,Shortest Path,Heap (Priority Queue)	Medium
1787	Make the XOR of All Segments Equal to Zero	Bit Manipulation,Array,Dynamic Programming	Hard
1788	Maximize the Beauty of the Garden	Greedy,Array,Prefix Sum	Hard	🔒
1789	Primary Department for Each Employee	Database	Easy	🔒
1790	Check if One String Swap Can Make Strings Equal	Hash Table,String,Counting	Easy
1791	Find Center of Star Graph	Graph	Easy
1792	Maximum Average Pass Ratio	Greedy,Array,Heap (Priority Queue)	Medium
1793	Maximum Score of a Good Subarray	Stack,Array,Two Pointers,Binary Search,Monotonic Stack	Hard
1794	Count Pairs of Equal Substrings With Minimum Difference	Greedy,Hash Table,String	Medium	🔒
1795	Rearrange Products Table	Database	Easy	🔒
1797	Design Authentication Manager	Design,Hash Table	Medium
1798	Maximum Number of Consecutive Values You Can Make	Greedy,Array	Medium
1799	Maximize Score After N Operations	Bit Manipulation,Array,Math,Dynamic Programming,Backtracking,Bitmask,Number Theory	Hard
1800	Maximum Ascending Subarray Sum	Array	Easy
1801	Number of Orders in the Backlog	Array,Simulation,Heap (Priority Queue)	Medium
1802	Maximum Value at a Given Index in a Bounded Array	Greedy,Binary Search	Medium
1803	Count Pairs With XOR in a Range	Bit Manipulation,Trie,Array	Hard
1804	Implement Trie II (Prefix Tree)	Design,Trie,Hash Table,String	Medium	🔒
1805	Number of Different Integers in a String	Hash Table,String	Easy
1806	Minimum Number of Operations to Reinitialize a Permutation	Array,Math,Simulation	Medium
1807	Evaluate the Bracket Pairs of a String	Array,Hash Table,String	Medium
1808	Maximize Number of Nice Divisors	Recursion,Math	Hard
1812	Determine Color of a Chessboard Square	Math,String	Easy
1813	Sentence Similarity III	Array,Two Pointers,String	Medium
1814	Count Nice Pairs in an Array	Array,Hash Table,Math,Counting	Medium
1815	Maximum Number of Groups Getting Fresh Donuts	Bit Manipulation,Memoization,Array,Dynamic Programming,Bitmask	Hard
1816	Truncate Sentence	Array,String	Easy
1817	Finding the Users Active Minutes	Array,Hash Table	Medium
1818	Minimum Absolute Sum Difference	Greedy,Array,Binary Search,Ordered Set	Medium
1819	Number of Different Subsequences GCDs	Array,Math,Counting,Number Theory	Hard
1820	Maximum Number of Accepted Invitations	Array,Backtracking,Matrix	Medium	🔒
1821	Find Customers With Positive Revenue this Year	Database	Easy	🔒
1822	Sign of the Product of an Array	Array,Math	Easy
1826	Faulty Sensor	Array,Two Pointers	Easy	🔒
1827	Minimum Operations to Make the Array Increasing	Greedy,Array	Easy
1828	Queries on Number of Points Inside a Circle	Geometry,Array,Math	Medium
1829	Maximum XOR for Each Query	Bit Manipulation,Array,Prefix Sum	Medium
1830	Minimum Number of Operations to Make String Sorted	Math,String,Combinatorics	Hard
1831	Maximum Transaction Each Day	Database	Medium	🔒
1836	Remove Duplicates From an Unsorted Linked List	Hash Table,Linked List	Medium	🔒
1837	Sum of Digits in Base K	Math	Easy
1838	Frequency of the Most Frequent Element	Array,Binary Search,Prefix Sum,Sliding Window	Medium
1839	Longest Substring Of All Vowels in Order	String,Sliding Window	Medium
1840	Maximum Building Height	Array,Math	Hard
1841	League Statistics	Database	Medium	🔒
1842	Next Palindrome Using Same Digits	Two Pointers,String	Hard	🔒
1843	Suspicious Bank Accounts	Database	Medium	🔒
1848	Minimum Distance to the Target Element	Array	Easy
1849	Splitting a String Into Descending Consecutive Values	String,Backtracking	Medium
1850	Minimum Adjacent Swaps to Reach the Kth Smallest Number	Greedy,Two Pointers,String	Medium
1851	Minimum Interval to Include Each Query	Array,Binary Search,Sorting,Line Sweep,Heap (Priority Queue)	Hard
1854	Maximum Population Year	Array,Counting	Easy
1855	Maximum Distance Between a Pair of Values	Greedy,Array,Two Pointers,Binary Search	Medium
1856	Maximum Subarray Min-Product	Stack,Array,Prefix Sum,Monotonic Stack	Medium
1857	Largest Color Value in a Directed Graph	Graph,Topological Sort,Memoization,Hash Table,Dynamic Programming,Counting	Hard
1859	Sorting the Sentence	String,Sorting	Easy
1860	Incremental Memory Leak	Simulation	Medium
1861	Rotating the Box	Array,Two Pointers,Matrix	Medium
1862	Sum of Floored Pairs	Array,Math,Binary Search,Prefix Sum	Hard
1863	Sum of All Subset XOR Totals	Bit Manipulation,Array,Backtracking	Easy
1864	Minimum Number of Swaps to Make the Binary String Alternating	Greedy,String	Medium
1865	Finding Pairs With a Certain Sum	Design,Array,Hash Table	Medium
1866	Number of Ways to Rearrange Sticks With K Sticks Visible	Math,Dynamic Programming,Combinatorics	Hard
1869	Longer Contiguous Segments of Ones than Zeros	String	Easy
1870	Minimum Speed to Arrive on Time	Array,Binary Search	Medium
1871	Jump Game VII	Two Pointers,String,Prefix Sum	Medium
1872	Stone Game VIII	Array,Math,Dynamic Programming,Game Theory,Prefix Sum	Hard
1876	Substrings of Size Three with Distinct Characters	Hash Table,String,Counting,Sliding Window	Easy
1877	Minimize Maximum Pair Sum in Array	Greedy,Array,Two Pointers,Sorting	Medium
1878	Get Biggest Three Rhombus Sums in a Grid	Array,Math,Matrix,Prefix Sum,Sorting,Heap (Priority Queue)	Medium
1879	Minimum XOR Sum of Two Arrays	Bit Manipulation,Array,Dynamic Programming,Bitmask	Hard
1881	Maximum Value after Insertion	Greedy,String	Medium
1884	Egg Drop With 2 Eggs and N Floors	Math,Dynamic Programming	Medium
1895	Largest Magic Square	Array,Matrix,Prefix Sum	Medium
1902	Depth of BST Given Insertion Order	Tree,Binary Search Tree,Binary Tree,Ordered Set	Medium	🔒
1908	Game of Nim	Bit Manipulation,Brainteaser,Array,Math,Dynamic Programming,Game Theory	Medium	🔒
1910	Remove All Occurrences of a Substring	String	Medium
1916	Count Ways to Build Rooms in an Ant Colony	Tree,Graph,Topological Sort,Math,Dynamic Programming,Combinatorics	Hard
1917	Leetcodify Friends Recommendations	Database	Hard	🔒
1918	Kth Smallest Subarray Sum	Array,Binary Search,Sliding Window	Medium	🔒
1919	Leetcodify Similar Friends		Hard	🔒
1922	Count Good Numbers	Recursion,Math	Medium
1924	Erect the Fence II	Geometry,Array,Math	Hard	🔒
1928	Minimum Cost to Reach Destination in Time	Graph,Dynamic Programming	Hard
1929	Concatenation of Array	Array	Easy
1930	Unique Length-3 Palindromic Subsequences	Hash Table,String,Prefix Sum	Medium
1931	Painting a Grid With Three Different Colors	Dynamic Programming	Hard
1932	Merge BSTs to Create Single BST	Tree,Depth-First Search,Hash Table,Binary Search,Binary Tree	Hard
1933	Check if String Is Decomposable Into Value-Equal Substrings	String	Easy	🔒
1934	Confirmation Rate		Medium	🔒
1935	Maximum Number of Words You Can Type	Hash Table,String	Easy
1936	Add Minimum Number of Rungs		Medium
1937	Maximum Number of Points with Cost		Medium
1938	Maximum Genetic Difference Query		Hard
1939	Users That Actively Request Confirmation Messages		Easy	🔒
1940	Longest Common Subsequence Between Sorted Arrays	Array,Hash Table,Counting	Medium	🔒
1944	Number of Visible People in a Queue	Stack,Array,Monotonic Stack	Hard
1945	Sum of Digits of String After Convert	String,Simulation	Easy
1946	Largest Number After Mutating Substring	Greedy,Array,String	Medium
1947	Maximum Compatibility Score Sum	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Medium
1948	Delete Duplicate Folders in System	Trie,Array,Hash Table,String,Hash Function	Hard
1949	Strong Friendship		Medium	🔒
1950	Maximum of Minimum Values in All Subarrays		Medium	🔒
1951	All the Pairs With the Maximum Number of Common Followers		Medium	🔒
1952	Three Divisors	Math	Easy
1953	Maximum Number of Weeks for Which You Can Work	Greedy,Array	Medium
1955	Count Number of Special Subsequences	Array,Dynamic Programming	Hard
1956	Minimum Time For K Virus Variants to Spread	Geometry,Array,Math,Binary Search,Enumeration	Hard	🔒
1957	Delete Characters to Make Fancy String	String	Easy
1958	Check if Move is Legal	Array,Enumeration,Matrix	Medium
1959	Minimum Total Space Wasted With K Resizing Operations	Array,Dynamic Programming	Medium
1960	Maximum Product of the Length of Two Palindromic Substrings	String,Hash Function,Rolling Hash	Hard
1961	Check If String Is a Prefix of Array	Array,String	Easy
1962	Remove Stones to Minimize the Total	Array,Heap (Priority Queue)	Medium
1963	Minimum Number of Swaps to Make the String Balanced	Stack,Greedy,Two Pointers,String	Medium
1964	Find the Longest Valid Obstacle Course at Each Position	Binary Indexed Tree,Array,Binary Search	Hard
1967	Number of Strings That Appear as Substrings in Word	String	Easy
1968	Array With Elements Not Equal to Average of Neighbors	Greedy,Array,Sorting	Medium
1969	Minimum Non-Zero Product of the Array Elements	Greedy,Recursion,Math	Medium
1970	Last Day Where You Can Still Cross	Depth-First Search,Breadth-First Search,Union Find,Array,Binary Search,Matrix	Hard
1971	Find if Path Exists in Graph	Depth-First Search,Breadth-First Search,Graph	Easy
1972	First and Last Call On the Same Day		Hard	🔒
1973	Count Nodes Equal to Sum of Descendants		Medium	🔒
1974	Minimum Time to Type Word Using Special Typewriter	Greedy,String	Easy
1975	Maximum Matrix Sum	Greedy,Array,Matrix	Medium
1976	Number of Ways to Arrive at Destination	Graph,Topological Sort,Dynamic Programming,Shortest Path	Medium
1977	Number of Ways to Separate Numbers	String,Dynamic Programming,Suffix Array	Hard
1978	Employees Whose Manager Left the Company		Easy	🔒
1979	Find Greatest Common Divisor of Array	Array,Math	Easy
1988	Find Cutoff Score for Each School		Medium	🔒
1989	Maximum Number of People That Can Be Caught in Tag		Medium	🔒
1990	Count the Number of Experiments		Easy	🔒
1991	Find the Middle Index in Array	Array,Prefix Sum	Easy
1992	Find All Groups of Farmland	Depth-First Search,Breadth-First Search,Array,Matrix	Medium
1993	Operations on Tree	Tree,Breadth-First Search,Design,Hash Table	Medium
1994	The Number of Good Subsets	Bit Manipulation,Array,Math,Dynamic Programming,Bitmask	Hard
1995	Count Special Quadruplets	Array,Enumeration	Easy
1996	The Number of Weak Characters in the Game	Stack,Greedy,Array,Sorting,Monotonic Stack	Medium
1997	First Day Where You Have Been in All the Rooms	Array,Dynamic Programming	Medium
1998	GCD Sort of an Array	Union Find,Array,Math,Sorting	Hard
1999	Smallest Greater Multiple Made of Two Digits		Medium	🔒
2000	Reverse Prefix of Word	Two Pointers,String	Easy
2001	Number of Pairs of Interchangeable Rectangles	Array,Hash Table,Math,Counting,Number Theory	Medium
2002	Maximum Product of the Length of Two Palindromic Subsequences	Bit Manipulation,String,Dynamic Programming,Backtracking,Bitmask	Medium
2003	Smallest Missing Genetic Value in Each Subtree	Tree,Depth-First Search,Union Find,Dynamic Programming	Hard
2004	The Number of Seniors and Juniors to Join the Company		Hard	🔒
2005	Subtree Removal Game with Fibonacci Tree		Hard	🔒
2009	Minimum Number of Operations to Make Array Continuous	Array,Binary Search	Hard
2010	The Number of Seniors and Juniors to Join the Company II		Hard	🔒
2011	Final Value of Variable After Performing Operations	Array,String,Simulation	Easy
2012	Sum of Beauty in the Array	Array	Medium
2013	Detect Squares	Design,Array,Hash Table,Counting	Medium
2014	Longest Subsequence Repeated k Times	Greedy,String,Backtracking,Counting,Enumeration	Hard
2015	Average Height of Buildings in Each Segment		Medium	🔒
2016	Maximum Difference Between Increasing Elements	Array	Easy
2017	Grid Game	Array,Matrix,Prefix Sum	Medium
2018	Check if Word Can Be Placed In Crossword	Array,Enumeration,Matrix	Medium
2019	The Score of Students Solving Math Expression	Stack,Memoization,Array,Math,String,Dynamic Programming	Hard
2020	Number of Accounts That Did Not Stream		Medium	🔒
2021	Brightest Position on Street		Medium	🔒
2022	Convert 1D Array Into 2D Array		Easy
2023	Number of Pairs of Strings With Concatenation Equal to Target		Medium
2024	Maximize the Confusion of an Exam		Medium
2025	Maximum Number of Ways to Partition an Array		Hard
2027	Minimum Moves to Convert String		Easy
2028	Find Missing Observations		Medium
2029	Stone Game IX		Medium
2030	Smallest K-Length Subsequence With Occurrences of a Letter		Hard

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