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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
0020	Valid Parentheses	Stack,String	Easy
0027	Remove Element	Array,Two Pointers	Easy
0037	Sudoku Solver	Array,Backtracking,Matrix	Hard
0046	Permutations	Array,Backtracking	Medium
0056	Merge Intervals	Array,Sorting	Medium
0058	Length of Last Word	String	Easy
0059	Spiral Matrix II	Array,Matrix,Simulation	Medium
0060	Permutation Sequence	Recursion,Math	Hard
0061	Rotate List	Linked List,Two Pointers	Medium
0062	Unique Paths	Math,Dynamic Programming,Combinatorics	Medium
0063	Unique Paths II	Array,Dynamic Programming,Matrix	Medium
0064	Minimum Path Sum	Array,Dynamic Programming,Matrix	Medium
0079	Word Search	Array,Backtracking,Matrix	Medium
0080	Remove Duplicates from Sorted Array II	Array,Two Pointers	Medium
0081	Search in Rotated Sorted Array II	Array,Binary Search	Medium
0082	Remove Duplicates from Sorted List II	Linked List,Two Pointers	Medium
0083	Remove Duplicates from Sorted List	Linked List	Easy
0084	Largest Rectangle in Histogram	Stack,Array,Monotonic Stack	Hard
0085	Maximal Rectangle	Stack,Array,Dynamic Programming,Matrix,Monotonic Stack	Hard
0086	Partition List	Linked List,Two Pointers	Medium
0087	Scramble String	String,Dynamic Programming	Hard
0088	Merge Sorted Array	Array,Two Pointers,Sorting	Easy
0089	Gray Code	Bit Manipulation,Math,Backtracking	Medium
0090	Subsets II	Bit Manipulation,Array,Backtracking	Medium
0091	Decode Ways	String,Dynamic Programming	Medium
0092	Reverse Linked List II	Linked List	Medium
0093	Restore IP Addresses	String,Backtracking	Medium
0094	Binary Tree Inorder Traversal	Stack,Tree,Depth-First Search,Binary Tree	Easy
0095	Unique Binary Search Trees II	Tree,Binary Search Tree,Dynamic Programming,Backtracking,Binary Tree	Medium
0096	Unique Binary Search Trees	Tree,Binary Search Tree,Math,Dynamic Programming,Binary Tree	Medium
0097	Interleaving String	String,Dynamic Programming	Medium
0098	Validate Binary Search Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
0099	Recover Binary Search Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium
0100	Same Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0101	Symmetric Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0102	Binary Tree Level Order Traversal	Tree,Breadth-First Search,Binary Tree	Medium
0103	Binary Tree Zigzag Level Order Traversal	Tree,Breadth-First Search,Binary Tree	Medium
0104	Maximum Depth of Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0105	Construct Binary Tree from Preorder and Inorder Traversal	Tree,Array,Hash Table,Divide and Conquer,Binary Tree	Medium
0106	Construct Binary Tree from Inorder and Postorder Traversal	Tree,Array,Hash Table,Divide and Conquer,Binary Tree	Medium
0107	Binary Tree Level Order Traversal II	Tree,Breadth-First Search,Binary Tree	Medium
0108	Convert Sorted Array to Binary Search Tree	Tree,Binary Search Tree,Array,Divide and Conquer,Binary Tree	Easy
0109	Convert Sorted List to Binary Search Tree	Tree,Binary Search Tree,Linked List,Divide and Conquer,Binary Tree	Medium
0110	Balanced Binary Tree	Tree,Depth-First Search,Binary Tree	Easy
0111	Minimum Depth of Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Easy
0112	Path Sum	Tree,Depth-First Search,Binary Tree	Easy
0113	Path Sum II	Tree,Depth-First Search,Backtracking,Binary Tree	Medium
0114	Flatten Binary Tree to Linked List	Stack,Tree,Depth-First Search,Linked List,Binary Tree	Medium
0130	Surrounded Regions	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
0131	Palindrome Partitioning	String,Dynamic Programming,Backtracking	Medium
0132	Palindrome Partitioning II	String,Dynamic Programming	Hard
0133	Clone Graph	Depth-First Search,Breadth-First Search,Graph,Hash Table	Medium
0134	Gas Station	Greedy,Array	Medium
0135	Candy	Greedy,Array	Hard
0136	Single Number	Bit Manipulation,Array	Easy
0137	Single Number II	Bit Manipulation,Array	Medium
0138	Copy List with Random Pointer	Hash Table,Linked List	Medium
0139	Word Break	Trie,Memoization,Hash Table,String,Dynamic Programming	Medium
0140	Word Break II	Trie,Memoization,Hash Table,String,Dynamic Programming,Backtracking	Hard
0141	Linked List Cycle	Hash Table,Linked List,Two Pointers	Easy
0142	Linked List Cycle II	Hash Table,Linked List,Two Pointers	Medium
0143	Reorder List	Stack,Recursion,Linked List,Two Pointers	Medium
0144	Binary Tree Preorder Traversal	Stack,Tree,Depth-First Search,Binary Tree	Easy
0145	Binary Tree Postorder Traversal	Stack,Tree,Depth-First Search,Binary Tree	Easy
0146	LRU Cache	Design,Hash Table,Linked List,Doubly-Linked List	Medium
0147	Insertion Sort List	Linked List,Sorting	Medium
0148	Sort List	Linked List,Two Pointers,Divide and Conquer,Sorting,Merge Sort	Medium
0149	Max Points on a Line	Geometry,Hash Table,Math	Hard
0150	Evaluate Reverse Polish Notation	Stack,Array,Math	Medium
0151	Reverse Words in a String	Two Pointers,String	Medium
0152	Maximum Product Subarray	Array,Dynamic Programming	Medium
0153	Find Minimum in Rotated Sorted Array	Array,Binary Search	Medium
0154	Find Minimum in Rotated Sorted Array II	Array,Binary Search	Hard
0155	Min Stack	Stack,Design	Easy
0156	Binary Tree Upside Down	Tree,Depth-First Search,Binary Tree	Medium	🔒
0157	Read N Characters Given Read4	String,Interactive,Simulation	Easy	🔒
0158	Read N Characters Given Read4 II - Call multiple times	String,Interactive,Simulation	Hard	🔒
0159	Longest Substring with At Most Two Distinct Characters	Hash Table,String,Sliding Window	Medium	🔒
0160	Intersection of Two Linked Lists	Hash Table,Linked List,Two Pointers	Easy
0161	One Edit Distance	Two Pointers,String	Medium	🔒
0162	Find Peak Element	Array,Binary Search	Medium
0163	Missing Ranges	Array	Easy	🔒
0164	Maximum Gap	Array,Bucket Sort,Radix Sort,Sorting	Hard
0165	Compare Version Numbers	Two Pointers,String	Medium
0166	Fraction to Recurring Decimal	Hash Table,Math,String	Medium
0167	Two Sum II - Input array is sorted	Array,Two Pointers,Binary Search	Easy
0171	Excel Sheet Column Number	Math,String	Easy
0177	Nth Highest Salary	Database	Medium
0178	Rank Scores	Database	Medium
0179	Largest Number	Greedy,String,Sorting	Medium
0180	Consecutive Numbers	Database	Medium
0181	Employees Earning More Than Their Managers	Database	Easy
0182	Duplicate Emails	Database	Easy
0183	Customers Who Never Order	Database	Easy
0184	Department Highest Salary	Database	Medium
0185	Department Top Three Salaries	Database	Hard
0186	Reverse Words in a String II	Two Pointers,String	Medium	🔒
0187	Repeated DNA Sequences	Bit Manipulation,Hash Table,String,Sliding Window,Hash Function,Rolling Hash	Medium
0188	Best Time to Buy and Sell Stock IV	Array,Dynamic Programming	Hard
0189	Rotate Array	Array,Math,Two Pointers	Medium
0190	Reverse Bits	Bit Manipulation,Divide and Conquer	Easy
0191	Number of 1 Bits	Bit Manipulation	Easy
0192	Word Frequency	Shell	Medium
0193	Valid Phone Numbers	Shell	Easy
0194	Transpose File	Shell	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
0241	Different Ways to Add Parentheses	Recursion,Memoization,Math,String,Dynamic Programming	Medium
0257	Binary Tree Paths	Tree,Depth-First Search,String,Binary Tree	Easy
0258	Add Digits	Math,Number Theory,Simulation	Easy
0259	3Sum Smaller	Array,Two Pointers,Binary Search,Sorting	Medium	🔒
0260	Single Number III	Bit Manipulation,Array	Medium
0261	Graph Valid Tree	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium	🔒
0262	Trips and Users	Database	Hard
0263	Ugly Number	Math	Easy
0264	Ugly Number II	Hash Table,Math,Dynamic Programming,Heap (Priority Queue)	Medium
0279	Perfect Squares	Breadth-First Search,Math,Dynamic Programming	Medium
0280	Wiggle Sort	Greedy,Array,Sorting	Medium	🔒
0281	Zigzag Iterator	Design,Queue,Array,Iterator	Medium	🔒
0282	Expression Add Operators	Math,String,Backtracking	Hard
0283	Move Zeroes	Array,Two Pointers	Easy
0284	Peeking Iterator	Design,Array,Iterator	Medium
0285	Inorder Successor in BST	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Medium	🔒
0286	Walls and Gates	Breadth-First Search,Array,Matrix	Medium	🔒
0287	Find the Duplicate Number	Bit Manipulation,Array,Two Pointers,Binary Search	Medium
0288	Unique Word Abbreviation	Design,Array,Hash Table,String	Medium	🔒
0289	Game of Life	Array,Matrix,Simulation	Medium
0290	Word Pattern	Hash Table,String	Easy
0291	Word Pattern II	Hash Table,String,Backtracking	Medium	🔒
0292	Nim Game	Brainteaser,Math,Game Theory	Easy
0293	Flip Game	String	Easy	🔒
0294	Flip Game II	Memoization,Math,Dynamic Programming,Backtracking,Game Theory	Medium	🔒
0295	Find Median from Data Stream	Design,Two Pointers,Data Stream,Sorting,Heap (Priority Queue)	Hard
0296	Best Meeting Point	Array,Math,Matrix,Sorting	Hard	🔒
0297	Serialize and Deserialize Binary Tree	Tree,Depth-First Search,Breadth-First Search,Design,String,Binary Tree	Hard
0298	Binary Tree Longest Consecutive Sequence	Tree,Depth-First Search,Binary Tree	Medium	🔒
0299	Bulls and Cows	Hash Table,String,Counting	Medium
0300	Longest Increasing Subsequence	Array,Binary Search,Dynamic Programming	Medium
0301	Remove Invalid Parentheses	Breadth-First Search,String,Backtracking	Hard
0302	Smallest Rectangle Enclosing Black Pixels	Depth-First Search,Breadth-First Search,Array,Binary Search,Matrix	Hard	🔒
0303	Range Sum Query - Immutable	Design,Array,Prefix Sum	Easy
0304	Range Sum Query 2D - Immutable	Design,Array,Matrix,Prefix Sum	Medium
0305	Number of Islands II	Union Find,Array	Hard	🔒
0306	Additive Number	String,Backtracking	Medium
0307	Range Sum Query - Mutable	Design,Binary Indexed Tree,Segment Tree,Array	Medium
0308	Range Sum Query 2D - Mutable	Design,Binary Indexed Tree,Segment Tree,Array,Matrix	Hard	🔒
0309	Best Time to Buy and Sell Stock with Cooldown	Array,Dynamic Programming	Medium
0310	Minimum Height Trees	Depth-First Search,Breadth-First Search,Graph,Topological Sort	Medium
0311	Sparse Matrix Multiplication	Array,Hash Table,Matrix	Medium	🔒
0312	Burst Balloons	Array,Dynamic Programming	Hard
0313	Super Ugly Number	Array,Hash Table,Math,Dynamic Programming,Heap (Priority Queue)	Medium
0314	Binary Tree Vertical Order Traversal	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium	🔒
0329	Longest Increasing Path in a Matrix	Depth-First Search,Breadth-First Search,Graph,Topological Sort,Memoization,Dynamic Programming	Hard
0349	Intersection of Two Arrays	Array,Hash Table,Two Pointers,Binary Search,Sorting	Easy
0355	Design Twitter	Design,Hash Table,Linked List,Heap (Priority Queue)	Medium
0356	Line Reflection	Array,Hash Table,Math	Medium	🔒
0357	Count Numbers with Unique Digits	Math,Dynamic Programming,Backtracking	Medium
0358	Rearrange String k Distance Apart	Greedy,Hash Table,String,Counting,Sorting,Heap (Priority Queue)	Hard	🔒
0359	Logger Rate Limiter	Design,Hash Table	Easy	🔒
0360	Sort Transformed Array	Array,Math,Two Pointers,Sorting	Medium	🔒
0361	Bomb Enemy	Array,Dynamic Programming,Matrix	Medium	🔒
0362	Design Hit Counter	Design,Queue,Array,Hash Table,Binary Search	Medium	🔒
0363	Max Sum of Rectangle No Larger Than K	Array,Binary Search,Dynamic Programming,Matrix,Ordered Set	Hard
0364	Nested List Weight Sum II	Stack,Depth-First Search,Breadth-First Search	Medium	🔒
0368	Largest Divisible Subset	Array,Math,Dynamic Programming,Sorting	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
0381	Insert Delete GetRandom O(1) - Duplicates allowed	Design,Array,Hash Table,Math,Randomized	Hard
0382	Linked List Random Node	Reservoir Sampling,Linked List,Math,Randomized	Medium
0383	Ransom Note	Hash Table,String,Counting	Easy
0384	Shuffle an Array	Array,Math,Randomized	Medium
0385	Mini Parser	Stack,Depth-First Search,String	Medium
0386	Lexicographical Numbers	Depth-First Search,Trie	Medium
0387	First Unique Character in a String	Queue,Hash Table,String,Counting	Easy
0388	Longest Absolute File Path	Stack,Depth-First Search,String	Medium
0389	Find the Difference	Bit Manipulation,Hash Table,String,Sorting	Easy
0390	Elimination Game	Math	Medium
0391	Perfect Rectangle	Array,Line Sweep	Hard
0392	Is Subsequence	Two Pointers,String,Dynamic Programming	Easy
0393	UTF-8 Validation	Bit Manipulation,Array	Medium
0394	Decode String	Stack,Recursion,String	Medium
0395	Longest Substring with At Least K Repeating Characters	Hash Table,String,Divide and Conquer,Sliding Window	Medium
0396	Rotate Function	Math,Dynamic Programming	Medium
0397	Integer Replacement	Bit Manipulation,Memoization,Dynamic Programming	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
0418	Sentence Screen Fitting	String,Dynamic Programming	Medium	🔒
0438	Find All Anagrams in a String	Hash Table,String,Sliding Window	Medium
0439	Ternary Expression Parser	Stack,Recursion,String	Medium	🔒
0440	K-th Smallest in Lexicographical Order	Trie	Hard
0441	Arranging Coins	Math,Binary Search	Easy
0442	Find All Duplicates in an Array	Array,Hash Table	Medium
0443	String Compression	Two Pointers,String	Medium
0444	Sequence Reconstruction	Graph,Topological Sort,Array	Medium	🔒
0445	Add Two Numbers II	Stack,Linked List,Math	Medium
0446	Arithmetic Slices II - Subsequence	Array,Dynamic Programming	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	🔒
0471	Encode String with Shortest Length	String,Dynamic Programming	Hard	🔒
0498	Diagonal Traverse	Array,Matrix,Simulation	Medium
0500	Keyboard Row	Array,Hash Table,String	Easy
0501	Find Mode in Binary Search Tree	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Easy
0502	IPO	Greedy,Array,Sorting,Heap (Priority Queue)	Hard
0503	Next Greater Element II	Stack,Array,Monotonic Stack	Medium
0504	Base 7	Math	Easy
0505	The Maze II	Depth-First Search,Breadth-First Search,Graph,Shortest Path,Heap (Priority Queue)	Medium	🔒
0506	Relative Ranks	Array,Sorting,Heap (Priority Queue)	Easy
0507	Perfect Number	Math	Easy
0508	Most Frequent Subtree Sum	Tree,Depth-First Search,Hash Table,Binary Tree	Medium
0510	Inorder Successor in BST II	Tree,Binary Search Tree,Binary Tree	Medium	🔒
0511	Game Play Analysis I	Database	Easy	🔒
0512	Game Play Analysis II	Database	Easy	🔒
0513	Find Bottom Left Tree Value	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0514	Freedom Trail	Depth-First Search,Breadth-First Search,String,Dynamic Programming	Hard
0515	Find Largest Value in Each Tree Row	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0516	Longest Palindromic Subsequence	String,Dynamic Programming	Medium
0517	Super Washing Machines	Greedy,Array	Hard
0518	Coin Change 2	Array,Dynamic Programming	Medium
0520	Detect Capital	String	Easy
0521	Longest Uncommon Subsequence I	String	Easy
0522	Longest Uncommon Subsequence II	Array,Hash Table,Two Pointers,String,Sorting	Medium
0523	Continuous Subarray Sum	Array,Hash Table,Math,Prefix Sum	Medium
0524	Longest Word in Dictionary through Deleting	Array,Two Pointers,String,Sorting	Medium
0525	Contiguous Array	Array,Hash Table,Prefix Sum	Medium
0526	Beautiful Arrangement	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Medium
0527	Word Abbreviation	Greedy,Trie,Array,String,Sorting	Hard	🔒
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	🔒
0534	Game Play Analysis III	Database	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
0543	Diameter of Binary Tree	Tree,Depth-First Search,Binary Tree	Easy
0544	Output Contest Matches	Recursion,String,Simulation	Medium	🔒
0545	Boundary of Binary Tree	Tree,Depth-First Search,Binary Tree	Medium	🔒
0546	Remove Boxes	Memoization,Array,Dynamic Programming	Hard
0547	Number of Provinces	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0548	Split Array with Equal Sum	Array,Prefix Sum	Hard	🔒
0549	Binary Tree Longest Consecutive Sequence II	Tree,Depth-First Search,Binary Tree	Medium	🔒
0550	Game Play Analysis IV	Database	Medium	🔒
0551	Student Attendance Record I	String	Easy
0552	Student Attendance Record II	Dynamic Programming	Hard
0553	Optimal Division	Array,Math,Dynamic Programming	Medium
0554	Brick Wall	Array,Hash Table	Medium
0555	Split Concatenated Strings	Greedy,Array,String	Medium	🔒
0556	Next Greater Element III	Math,Two Pointers,String	Medium
0557	Reverse Words in a String III	Two Pointers,String	Easy
0560	Subarray Sum Equals K	Array,Hash Table,Prefix Sum	Medium
0561	Array Partition I	Greedy,Array,Counting Sort,Sorting	Easy
0562	Longest Line of Consecutive One in Matrix	Array,Dynamic Programming,Matrix	Medium	🔒
0563	Binary Tree Tilt	Tree,Depth-First Search,Binary Tree	Easy
0564	Find the Closest Palindrome	Math,String	Hard
0565	Array Nesting	Depth-First Search,Array	Medium
0566	Reshape the Matrix	Array,Matrix,Simulation	Easy
0567	Permutation in String	Hash Table,Two Pointers,String,Sliding Window	Medium
0568	Maximum Vacation Days	Array,Dynamic Programming,Matrix	Hard	🔒
0569	Median Employee Salary	Database	Hard	🔒
0570	Managers with at Least 5 Direct Reports	Database	Medium	🔒
0571	Find Median Given Frequency of Numbers	Database	Hard	🔒
0572	Subtree of Another Tree	Tree,Depth-First Search,Binary Tree,String Matching,Hash Function	Easy
0573	Squirrel Simulation	Array,Math	Medium	🔒
0574	Winning Candidate	Database	Medium	🔒
0575	Distribute Candies	Array,Hash Table	Easy
0576	Out of Boundary Paths	Dynamic Programming	Medium
0577	Employee Bonus	Database	Easy	🔒
0578	Get Highest Answer Rate Question	Database	Medium	🔒
0592	Fraction Addition and Subtraction	Math,String,Simulation	Medium
0594	Longest Harmonious Subsequence	Array,Hash Table,Sorting	Easy
0595	Big Countries	Database	Easy
0596	Classes More Than 5 Students	Database	Easy
0597	Friend Requests I Overall Acceptance Rate	Database	Easy	🔒
0598	Range Addition II	Array,Math	Easy
0599	Minimum Index Sum of Two Lists	Array,Hash Table,String	Easy
0600	Non-negative Integers without Consecutive Ones	Dynamic Programming	Hard
0601	Human Traffic of Stadium	Database	Hard
0602	Friend Requests II Who Has the Most Friends	Database	Medium	🔒
0603	Consecutive Available Seats	Database	Easy	🔒
0604	Design Compressed String Iterator	Design,Array,Hash Table,String,Iterator	Easy	🔒
0605	Can Place Flowers	Greedy,Array	Easy
0606	Construct String from Binary Tree	Tree,Depth-First Search,String,Binary Tree	Easy
0607	Sales Person	Database	Easy	🔒
0608	Tree Node	Database	Medium	🔒
0609	Find Duplicate File in System	Array,Hash Table,String	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
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
0638	Shopping Offers	Bit Manipulation,Memoization,Array,Dynamic Programming,Backtracking,Bitmask	Medium
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
0649	Dota2 Senate	Greedy,Queue,String	Medium
0650	2 Keys Keyboard	Math,Dynamic Programming	Medium
0651	4 Keys Keyboard	Math,Dynamic Programming	Medium	🔒
0652	Find Duplicate Subtrees	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0653	Two Sum IV - Input is a BST	Tree,Depth-First Search,Breadth-First Search,Binary Search Tree,Hash Table,Two Pointers,Binary Tree	Easy
0654	Maximum Binary Tree	Stack,Tree,Array,Divide and Conquer,Binary Tree,Monotonic Stack	Medium
0655	Print Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
0656	Coin Path	Array,Dynamic Programming	Hard	🔒
0657	Robot Return to Origin	String,Simulation	Easy
0658	Find K Closest Elements	Array,Two Pointers,Binary Search,Sorting,Heap (Priority Queue)	Medium
0659	Split Array into Consecutive Subsequences	Greedy,Array,Hash Table,Heap (Priority Queue)	Medium
0660	Remove 9	Math	Hard	🔒
0661	Image Smoother	Array,Matrix	Easy
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
0698	Partition to K Equal Sum Subsets	Bit Manipulation,Memoization,Array,Dynamic Programming,Backtracking,Bitmask	Medium
0704	Binary Search	Array,Binary Search	Easy
0707	Design Linked List	Design,Linked List	Medium
0708	Insert into a Sorted Circular Linked List	Linked List	Medium	🔒
0709	To Lower Case	String	Easy
0710	Random Pick with Blacklist	Hash Table,Math,Binary Search,Sorting,Randomized	Hard
0714	Best Time to Buy and Sell Stock with Transaction Fee	Greedy,Array,Dynamic Programming	Medium
0721	Accounts Merge	Depth-First Search,Breadth-First Search,Union Find,Array,String	Medium
0730	Count Different Palindromic Subsequences	String,Dynamic Programming	Hard
0740	Delete and Earn	Array,Hash Table,Dynamic Programming	Medium
0741	Cherry Pickup	Array,Dynamic Programming,Matrix	Hard
0742	Closest Leaf in a Binary Tree	Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium	🔒
0755	Pour Water	Array,Simulation	Medium	🔒
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
0787	Cheapest Flights Within K Stops	Depth-First Search,Breadth-First Search,Graph,Dynamic Programming,Shortest Path,Heap (Priority Queue)	Medium
0796	Rotate String	String,String Matching	Easy
0804	Unique Morse Code Words	Array,Hash Table,String	Easy
0813	Largest Sum of Averages	Array,Dynamic Programming	Medium
0820	Short Encoding of Words	Trie,Array,Hash Table,String	Medium
0821	Shortest Distance to a Character	Array,Two Pointers,String	Easy
0822	Card Flipping Game	Array,Hash Table	Medium
0823	Binary Trees With Factors	Array,Hash Table,Dynamic Programming	Medium
0827	Making A Large Island	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Hard
0843	Guess the Word	Array,Math,String,Game Theory,Interactive	Hard
0852	Peak Index in a Mountain Array	Array,Binary Search	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
0864	Shortest Path to Get All Keys	Bit Manipulation,Breadth-First Search	Hard
0865	Smallest Subtree with all the Deepest Nodes	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium
0866	Prime Palindrome	Math	Medium
0867	Transpose Matrix	Array,Matrix,Simulation	Easy
0868	Binary Gap	Bit Manipulation,Math	Easy
0869	Reordered Power of 2	Math,Counting,Enumeration,Sorting	Medium
0872	Leaf-Similar Trees	Tree,Depth-First Search,Binary Tree	Easy
0885	Spiral Matrix III	Array,Matrix,Simulation	Medium
0886	Possible Bipartition	Depth-First Search,Breadth-First Search,Union Find,Graph	Medium
0887	Super Egg Drop	Math,Binary Search,Dynamic Programming	Hard
0888	Fair Candy Swap	Array,Hash Table,Binary Search,Sorting	Easy
0889	Construct Binary Tree from Preorder and Postorder Traversal	Tree,Array,Hash Table,Divide and Conquer,Binary Tree	Medium
0890	Find and Replace Pattern	Array,Hash Table,String	Medium
0891	Sum of Subsequence Widths	Array,Math,Sorting	Hard
0892	Surface Area of 3D Shapes	Geometry,Array,Math,Matrix	Easy
0894	All Possible Full Binary Trees	Tree,Recursion,Memoization,Dynamic Programming,Binary Tree	Medium
0895	Maximum Frequency Stack	Stack,Design,Hash Table,Ordered Set	Hard
0896	Monotonic Array	Array	Easy
0897	Increasing Order Search Tree	Stack,Tree,Depth-First Search,Binary Search Tree,Binary Tree	Easy
0898	Bitwise ORs of Subarrays	Bit Manipulation,Array,Dynamic Programming	Medium
0899	Orderly Queue	Math,String,Sorting	Hard
0900	RLE Iterator	Design,Array,Counting,Iterator	Medium
0901	Online Stock Span	Stack,Design,Data Stream,Monotonic Stack	Medium
0902	Numbers At Most N Given Digit Set	Array,Math,Binary Search,Dynamic Programming	Hard
0903	Valid Permutations for DI Sequence	Dynamic Programming	Hard
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
0919	Complete Binary Tree Inserter	Tree,Breadth-First Search,Design,Binary Tree	Medium
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
0931	Minimum Falling Path Sum	Array,Dynamic Programming,Matrix	Medium
0932	Beautiful Array	Array,Math,Divide and Conquer	Medium
0933	Number of Recent Calls	Design,Queue,Data Stream	Easy
0934	Shortest Bridge	Depth-First Search,Breadth-First Search,Array,Matrix	Medium
0935	Knight Dialer	Dynamic Programming	Medium
0936	Stamping The Sequence	Stack,Greedy,Queue,String	Hard
0937	Reorder Data in Log Files	Array,String,Sorting	Easy
0938	Range Sum of BST	Tree,Depth-First Search,Binary Search Tree,Binary Tree	Easy
0939	Minimum Area Rectangle	Geometry,Array,Hash Table,Math,Sorting	Medium
0940	Distinct Subsequences II	String,Dynamic Programming	Hard
0941	Valid Mountain Array	Array	Easy
0942	DI String Match	Greedy,Array,Math,Two Pointers,String	Easy
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
0969	Pancake Sorting	Greedy,Array,Two Pointers,Sorting	Medium
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
0980	Unique Paths III	Bit Manipulation,Array,Backtracking,Matrix	Hard
0981	Time Based Key-Value Store	Design,Hash Table,String,Binary Search	Medium
0982	Triples with Bitwise AND Equal To Zero	Bit Manipulation,Array,Hash Table	Hard
0983	Minimum Cost For Tickets	Array,Dynamic Programming	Medium
0984	String Without AAA or BBB	Greedy,String	Medium
0985	Sum of Even Numbers After Queries	Array,Simulation	Medium
0986	Interval List Intersections	Array,Two Pointers	Medium
0987	Vertical Order Traversal of a Binary Tree	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Hard
0988	Smallest String Starting From Leaf	Tree,Depth-First Search,String,Binary Tree	Medium
0989	Add to Array-Form of Integer	Array,Math	Easy
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
1029	Two City Scheduling	Greedy,Array,Sorting	Medium
1054	Distant Barcodes	Greedy,Array,Hash Table,Counting,Sorting,Heap (Priority Queue)	Medium
1055	Shortest Way to Form String	Greedy,String,Dynamic Programming	Medium	🔒
1057	Campus Bikes	Greedy,Array,Sorting	Medium	🔒
1058	Minimize Rounding Error to Meet Target	Greedy,Array,Math,String	Medium	🔒
1059	All Paths from Source Lead to Destination	Depth-First Search,Graph	Medium	🔒
1060	Missing Element in Sorted Array	Array,Binary Search	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	🔒
1073	Adding Two Negabinary Numbers	Array,Math	Medium
1078	Occurrences After Bigram	String	Easy
1080	Insufficient Nodes in Root to Leaf Paths	Tree,Depth-First Search,Binary Tree	Medium
1082	Sales Analysis I	Database	Easy	🔒
1083	Sales Analysis II	Database	Easy	🔒
1084	Sales Analysis III	Database	Easy	🔒
1087	Brace Expansion	Breadth-First Search,String,Backtracking	Medium	🔒
1089	Duplicate Zeros	Array,Two Pointers	Easy
1093	Statistics from a Large Sample	Math,Two Pointers,Probability and Statistics	Medium
1094	Car Pooling	Array,Prefix Sum,Sorting,Simulation,Heap (Priority Queue)	Medium
1095	Find in Mountain Array	Array,Binary Search,Interactive	Hard
1096	Brace Expansion II	Stack,Breadth-First Search,String,Backtracking	Hard
1097	Game Play Analysis V	Database	Hard	🔒
1098	Unpopular Books	Database	Medium	🔒
1103	Distribute Candies to People	Math,Simulation	Easy
1104	Path In Zigzag Labelled Binary Tree	Tree,Math,Binary Tree	Medium
1105	Filling Bookcase Shelves	Array,Dynamic Programming	Medium
1106	Parsing A Boolean Expression	Stack,Recursion,String	Hard
1107	New Users Daily Count	Database	Medium	🔒
1108	Defanging an IP Address	String	Easy
1109	Corporate Flight Bookings	Array,Prefix Sum	Medium
1110	Delete Nodes And Return Forest	Tree,Depth-First Search,Binary Tree	Medium
1111	Maximum Nesting Depth of Two Valid Parentheses Strings	Stack,String	Medium
1114	Print in Order	Concurrency	Easy
1115	Print FooBar Alternately	Concurrency	Medium
1117	Building H2O	Concurrency	Medium
1130	Minimum Cost Tree From Leaf Values	Stack,Greedy,Dynamic Programming,Monotonic Stack	Medium
1138	Alphabet Board Path	Hash Table,String	Medium
1144	Decrease Elements To Make Array Zigzag	Greedy,Array	Medium
1148	Article Views I	Database	Easy	🔒
1149	Article Views II	Database	Medium	🔒
1155	Number of Dice Rolls With Target Sum	Dynamic Programming	Medium
1163	Last Substring in Lexicographical Order	Two Pointers,String	Hard
1173	Immediate Food Delivery I	Database	Easy	🔒
1174	Immediate Food Delivery II	Database	Medium	🔒
1179	Reformat Department Table	Database	Easy
1183	Maximum Number of Ones	Greedy,Heap (Priority Queue)	Hard	🔒
1189	Maximum Number of Balloons	Hash Table,String,Counting	Easy
1190	Reverse Substrings Between Each Pair of Parentheses	Stack,String	Medium
1191	K-Concatenation Maximum Sum	Array,Dynamic Programming	Medium
1192	Critical Connections in a Network	Depth-First Search,Graph,Biconnected Component	Hard
1193	Monthly Transactions I	Database	Medium	🔒
1195	Fizz Buzz Multithreaded	Concurrency	Medium
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
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	🔒
1216	Valid Palindrome III	String,Dynamic Programming	Hard	🔒
1218	Longest Arithmetic Subsequence of Given Difference	Array,Hash Table,Dynamic Programming	Medium
1227	Airplane Seat Assignment Probability	Brainteaser,Math,Dynamic Programming,Probability and Statistics	Medium
1231	Divide Chocolate	Array,Binary Search	Hard	🔒
1233	Remove Sub-Folders from the Filesystem	Trie,Array,String	Medium
1243	Array Transformation	Array,Simulation	Easy	🔒
1244	Design A Leaderboard	Design,Hash Table,Sorting	Medium	🔒
1245	Tree Diameter	Tree,Depth-First Search,Breadth-First Search	Medium	🔒
1246	Palindrome Removal	Array,Dynamic Programming	Hard	🔒
1256	Encode Number	Bit Manipulation,Math,String	Medium	🔒
1257	Smallest Common Region	Tree,Depth-First Search,Breadth-First Search,Array,Hash Table,String	Medium	🔒
1258	Synonymous Sentences	Union Find,Array,Hash Table,String,Backtracking	Medium	🔒
1261	Find Elements in a Contaminated Binary Tree	Tree,Depth-First Search,Breadth-First Search,Design,Binary Tree	Medium
1265	Print Immutable Linked List in Reverse	Stack,Recursion,Linked List,Two Pointers	Medium	🔒
1268	Search Suggestions System	Trie,Array,String	Medium
1270	All People Report to the Given Manager	Database	Medium	🔒
1271	Hexspeak	Math,String	Easy	🔒
1272	Remove Interval	Array	Medium	🔒
1273	Delete Tree Nodes	Tree,Depth-First Search,Breadth-First Search	Medium	🔒
1277	Count Square Submatrices with All Ones	Array,Dynamic Programming,Matrix	Medium
1278	Palindrome Partitioning III	String,Dynamic Programming	Hard
1279	Traffic Light Controlled Intersection	Concurrency	Easy	🔒
1280	Students and Examinations	Database	Easy	🔒
1281	Subtract the Product and Sum of Digits of an Integer	Math	Easy
1282	Group the People Given the Group Size They Belong To	Array,Hash Table	Medium
1283	Find the Smallest Divisor Given a Threshold	Array,Binary Search	Medium
1284	Minimum Number of Flips to Convert Binary Matrix to Zero Matrix	Bit Manipulation,Breadth-First Search,Array,Matrix	Hard
1285	Find the Start and End Number of Continuous Ranges	Database	Medium	🔒
1288	Remove Covered Intervals	Array,Sorting	Medium
1290	Convert Binary Number in a Linked List to Integer	Linked List,Math	Easy
1292	Maximum Side Length of a Square with Sum Less than or Equal to Threshold	Array,Binary Search,Matrix,Prefix Sum	Medium
1293	Shortest Path in a Grid with Obstacles Elimination	Breadth-First Search,Array,Matrix	Hard
1294	Weather Type in Each Country	Database	Easy	🔒
1295	Find Numbers with Even Number of Digits	Array	Easy
1296	Divide Array in Sets of K Consecutive Numbers	Greedy,Array,Hash Table,Sorting	Medium
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
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
1325	Delete Leaves With a Given Value	Tree,Depth-First Search,Breadth-First Search,Hash Table,Binary Tree	Medium
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
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
1355	Activity Participants	Database	Medium	🔒
1358	Number of Substrings Containing All Three Characters	Hash Table,String,Sliding Window	Medium
1364	Number of Trusted Contacts of a Customer	Database	Medium	🔒
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
1380	Lucky Numbers in a Matrix	Array,Matrix	Easy
1381	Design a Stack With Increment Operation	Stack,Design,Array	Medium
1384	Total Sales Amount by Year	Database	Hard	🔒
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
1390	Four Divisors	Array,Math	Medium
1393	Capital GainLoss	Database	Medium	🔒
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	🔒
1403	Minimum Subsequence in Non-Increasing Order	Greedy,Array,Sorting	Easy
1404	Number of Steps to Reduce a Number in Binary Representation to One	Bit Manipulation,String	Medium
1405	Longest Happy String	Greedy,String,Heap (Priority Queue)	Medium
1406	Stone Game III	Array,Math,Dynamic Programming,Game Theory	Hard
1407	Top Travellers	Database	Easy	🔒
1408	String Matching in an Array	String,String Matching	Easy
1409	Queries on a Permutation With Key	Binary Indexed Tree,Array,Simulation	Medium
1410	HTML Entity Parser	Hash Table,String	Medium
1411	Number of Ways to Paint N × 3 Grid	Dynamic Programming	Hard
1412	Find the Quiet Students in All Exams	Database	Hard	🔒
1413	Minimum Value to Get Positive Step by Step Sum	Array,Prefix Sum	Easy
1414	Find the Minimum Number of Fibonacci Numbers Whose Sum Is K	Greedy	Medium
1415	The k-th Lexicographical String of All Happy Strings of Length n	String,Backtracking	Medium
1416	Restore The Array	String,Dynamic Programming	Hard
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
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
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	🔒
1442	Count Triplets That Can Form Two Arrays of Equal XOR	Bit Manipulation,Array,Hash Table,Math,Prefix Sum	Medium
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
1451	Rearrange Words in a Sentence	String,Sorting	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
1456	Maximum Number of Vowels in a Substring of Given Length	String,Sliding Window	Medium
1457	Pseudo-Palindromic Paths in a Binary Tree	Bit Manipulation,Tree,Depth-First Search,Breadth-First Search,Binary Tree	Medium
1458	Max Dot Product of Two Subsequences	Array,Dynamic Programming	Hard
1459	Rectangles Area	Database	Medium	🔒
1464	Maximum Product of Two Elements in an Array	Array,Sorting,Heap (Priority Queue)	Easy
1465	Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts	Greedy,Array,Sorting	Medium
1466	Reorder Routes to Make All Paths Lead to the City Zero	Depth-First Search,Breadth-First Search,Graph	Medium
1467	Probability of a Two Boxes Having The Same Number of Distinct Balls	Math,Dynamic Programming,Backtracking,Combinatorics,Probability and Statistics	Hard
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
1475	Final Prices With a Special Discount in a Shop	Stack,Array,Monotonic Stack	Easy
1476	Subrectangle Queries	Design,Array,Matrix	Medium
1477	Find Two Non-overlapping Sub-arrays Each With Target Sum	Array,Hash Table,Binary Search,Dynamic Programming,Sliding Window	Medium
1478	Allocate Mailboxes	Array,Math,Dynamic Programming,Sorting	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
1483	Kth Ancestor of a Tree Node	Tree,Depth-First Search,Breadth-First Search,Design,Binary Search,Dynamic Programming	Hard
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
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
1517	Find Users With Valid E-Mails	Database	Easy	🔒
1519	Number of Nodes in the Sub-Tree With the Same Label	Tree,Depth-First Search,Breadth-First Search	Medium
1522	Diameter of N-Ary Tree	Tree,Depth-First Search	Medium	🔒
1523	Count Odd Numbers in an Interval Range	Math	Easy
1528	Shuffle String	Array,String	Easy
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
1550	Three Consecutive Odds	Array	Easy
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
1564	Put Boxes Into the Warehouse I	Greedy,Array,Sorting	Medium	🔒
1565	Unique Orders and Customers Per Month	Database	Easy	🔒
1566	Detect Pattern of Length M Repeated K or More Times	Array,Enumeration	Easy
1570	Dot Product of Two Sparse Vectors	Design,Array,Hash Table,Two Pointers	Medium	🔒
1571	Warehouse Manager	Database	Easy	🔒
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
1587	Bank Account Summary II	Database	Easy	🔒
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	🔒
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
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
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
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
1658	Minimum Operations to Reduce X to Zero	Array,Hash Table,Two Pointers,Binary Search,Prefix Sum	Medium
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
1672	Richest Customer Wealth	Array,Matrix	Easy
1673	Find the Most Competitive Subsequence	Stack,Greedy,Array,Monotonic Stack	Medium
1674	Minimum Moves to Make Array Complementary	Array,Hash Table,Prefix Sum	Medium
1675	Minimize Deviation in Array	Greedy,Array,Ordered Set,Heap (Priority Queue)	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	🔒
1684	Count the Number of Consistent Strings	Bit Manipulation,Array,Hash Table,String	Easy
1685	Sum of Absolute Differences in a Sorted Array	Array,Math,Prefix Sum	Medium
1686	Stone Game VI	Greedy,Array,Math,Game Theory,Sorting,Heap (Priority Queue)	Medium
1687	Delivering Boxes from Storage to Ports	Segment Tree,Queue,Array,Dynamic Programming,Monotonic Queue,Heap (Priority Queue)	Hard
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
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
1699	Number of Calls Between Two Persons	Database	Medium	🔒
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
1708	Largest Subarray Length K	Greedy,Array	Easy	🔒
1709	Biggest Window Between Visits	Database	Medium	🔒
1711	Count Good Meals	Array,Hash Table	Medium
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
1721	Swapping Nodes in a Linked List	Linked List,Two Pointers	Medium
1722	Minimize Hamming Distance After Swap Operations	Depth-First Search,Union Find,Array	Medium
1724	Checking Existence of Edge Length Limited Paths II	Union Find,Graph,Minimum Spanning Tree	Hard	🔒
1725	Number Of Rectangles That Can Form The Largest Square	Array	Easy
1727	Largest Submatrix With Rearrangements	Greedy,Array,Matrix,Sorting	Medium
1729	Find Followers Count	Database	Easy	🔒
1730	Shortest Path to Get Food	Breadth-First Search,Array,Matrix	Medium	🔒
1731	The Number of Employees Which Report to Each Employee	Database	Easy	🔒
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
1742	Maximum Number of Balls in a Box	Hash Table,Math,Counting	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	🔒
1748	Sum of Unique Elements	Array,Hash Table,Counting	Easy
1749	Maximum Absolute Sum of Any Subarray	Array,Dynamic Programming	Medium
1750	Minimum Length of String After Deleting Similar Ends	Two Pointers,String	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
1756	Design Most Recently Used Queue	Stack,Design,Array,Hash Table,Ordered Set	Medium	🔒
1757	Recyclable and Low Fat Products	Database	Easy	🔒
1759	Count Number of Homogenous Substrings	Math,String	Medium
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	🔒
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
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,Monotonic Stack	Hard
1794	Count Pairs of Equal Substrings With Minimum Difference	Greedy,Hash Table,String	Medium	🔒
1795	Rearrange Products Table	Database	Easy	🔒
1796	Second Largest Digit in a String	Hash Table,String	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
1807	Evaluate the Bracket Pairs of a String	Array,Hash Table,String	Medium
1809	Ad-Free Sessions	Database	Easy	🔒
1810	Minimum Path Cost in a Hidden Grid	Depth-First Search,Breadth-First Search,Graph,Interactive,Heap (Priority Queue)	Medium	🔒
1811	Find Interview Candidates	Database	Medium	🔒
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
1823	Find the Winner of the Circular Game	Recursion,Array,Math,Simulation	Medium
1824	Minimum Sideway Jumps	Greedy,Array,Dynamic Programming	Medium
1825	Finding MK Average	Design,Queue,Ordered Set,Heap (Priority Queue)	Hard
1826	Faulty Sensor	Array,Two Pointers	Easy	🔒
1831	Maximum Transaction Each Day	Database	Medium	🔒
1832	Check if the Sentence Is Pangram	Hash Table,String	Easy
1833	Maximum Ice Cream Bars	Greedy,Array,Sorting	Medium
1834	Single-Threaded CPU	Array,Sorting,Heap (Priority Queue)	Medium
1835	Find XOR Sum of All Pairs Bitwise AND	Bit Manipulation,Array,Math	Hard
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
1842	Next Palindrome Using Same Digits	Two Pointers,String	Hard	🔒
1843	Suspicious Bank Accounts	Database	Medium	🔒
1844	Replace All Digits with Characters	String	Easy
1845	Seat Reservation Manager	Design,Heap (Priority Queue)	Medium
1846	Maximum Element After Decreasing and Rearranging	Greedy,Array,Sorting	Medium
1847	Closest Room	Array,Binary Search,Sorting	Hard
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
1852	Distinct Numbers in Each Subarray	Array,Hash Table,Sliding Window	Medium	🔒
1853	Convert Date Format	Database	Easy	🔒
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
1858	Longest Word With All Prefixes	Depth-First Search,Trie	Medium	🔒
1859	Sorting the Sentence	String,Sorting	Easy
1860	Incremental Memory Leak	Simulation	Medium
1861	Rotating the Box	Array,Two Pointers,Matrix	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
1867	Orders With Maximum Quantity Above Average	Database	Medium	🔒
1868	Product of Two Run-Length Encoded Arrays	Array,Two Pointers	Medium	🔒
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
1873	Calculate Special Bonus	Database	Easy	🔒
1874	Minimize Product Sum of Two Arrays	Greedy,Array,Sorting	Medium	🔒
1875	Group Employees of the Same Salary	Database	Medium	🔒
1878	Get Biggest Three Rhombus Sums in a Grid	Array,Math,Matrix,Prefix Sum,Sorting,Heap (Priority Queue)	Medium
1880	Check if Word Equals Summation of Two Words	String	Easy
1881	Maximum Value after Insertion	Greedy,String	Medium
1882	Process Tasks Using Servers	Array,Heap (Priority Queue)	Medium
1883	Minimum Skips to Arrive at Meeting On Time	Array,Dynamic Programming	Hard
1884	Egg Drop With 2 Eggs and N Floors	Math,Dynamic Programming	Medium
1885	Count Pairs in Two Arrays	Array,Binary Search,Sorting	Medium	🔒
1886	Determine Whether Matrix Can Be Obtained By Rotation	Array,Matrix	Easy
1887	Reduction Operations to Make the Array Elements Equal	Array,Sorting	Medium
1888	Minimum Number of Flips to Make the Binary String Alternating	Greedy,String	Medium
1889	Minimum Space Wasted From Packaging	Array,Binary Search,Prefix Sum,Sorting	Hard
1892	Page Recommendations II	Database	Hard	🔒
1893	Check if All the Integers in a Range Are Covered	Array,Hash Table,Prefix Sum	Easy
1894	Find the Student that Will Replace the Chalk	Array,Binary Search,Prefix Sum,Simulation	Medium
1895	Largest Magic Square	Array,Matrix,Prefix Sum	Medium
1896	Minimum Cost to Change the Final Value of Expression	Stack,Math,String,Dynamic Programming	Hard
1897	Redistribute Characters to Make All Strings Equal	Hash Table,String,Counting	Easy
1898	Maximum Number of Removable Characters	Array,String,Binary Search	Medium
1899	Merge Triplets to Form Target Triplet	Greedy,Array	Medium
1900	The Earliest and Latest Rounds Where Players Compete	Memoization,Dynamic Programming	Hard
1901	Find a Peak Element II	Array,Binary Search,Divide and Conquer,Matrix	Medium
1902	Depth of BST Given Insertion Order	Tree,Binary Search Tree,Binary Tree,Ordered Set	Medium	🔒
1903	Largest Odd Number in String	Greedy,Math,String	Easy
1904	The Number of Full Rounds You Have Played	Math,String	Medium
1905	Count Sub Islands	Depth-First Search,Breadth-First Search,Union Find,Array,Matrix	Medium
1906	Minimum Absolute Difference Queries	Array,Hash Table	Medium
1907	Count Salary Categories	Database	Medium	🔒
1908	Game of Nim	Bit Manipulation,Brainteaser,Array,Math,Dynamic Programming,Game Theory	Medium	🔒
1909	Remove One Element to Make the Array Strictly Increasing	Array	Easy
1910	Remove All Occurrences of a Substring	String	Medium
1911	Maximum Alternating Subsequence Sum	Array,Dynamic Programming	Medium
1912	Design Movie Rental System	Design,Array,Hash Table,Ordered Set,Heap (Priority Queue)	Hard
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	🔒
1920	Build Array from Permutation	Array,Simulation	Easy
1921	Eliminate Maximum Number of Monsters	Greedy,Array,Sorting	Medium
1922	Count Good Numbers	Recursion,Math	Medium
1923	Longest Common Subpath	Array,Binary Search,Suffix Array,Hash Function,Rolling Hash	Hard
1924	Erect the Fence II	Geometry,Array,Math	Hard	🔒
1925	Count Square Sum Triples	Math,Enumeration	Easy
1926	Nearest Exit from Entrance in Maze	Breadth-First Search,Array,Matrix	Medium
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	🔒
1936	Add Minimum Number of Rungs		Medium
1937	Maximum Number of Points with Cost		Medium
1938	Maximum Genetic Difference Query		Hard
1940	Longest Common Subsequence Between Sorted Arrays	Array,Hash Table,Counting	Medium	🔒
1941	Check if All Characters Have Equal Number of Occurrences	Hash Table,String,Counting	Easy
1942	The Number of the Smallest Unoccupied Chair	Array,Ordered Set,Heap (Priority Queue)	Medium
1943	Describe the Painting	Array,Prefix Sum	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
1950	Maximum of Minimum Values in All Subarrays		Medium	🔒
1952	Three Divisors	Math	Easy
1953	Maximum Number of Weeks for Which You Can Work	Greedy,Array	Medium
1954	Minimum Garden Perimeter to Collect Enough Apples	Math,Binary Search	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
1965	Employees With Missing Information		Easy	🔒
1966	Binary Searchable Numbers in an Unsorted Array		Medium	🔒
1968	Array With Elements Not Equal to Average of Neighbors	Greedy,Array,Sorting	Medium
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
1980	Find Unique Binary String	Array,String,Backtracking	Medium
1981	Minimize the Difference Between Target and Chosen Elements	Array,Dynamic Programming,Matrix	Medium
1982	Find Array Given Subset Sums	Array,Divide and Conquer	Hard
1983	Widest Pair of Indices With Equal Range Sum		Medium	🔒
1984	Minimum Difference Between Highest and Lowest of K Scores	Array,Sorting	Easy
1985	Find the Kth Largest Integer in the Array	Array,String,Divide and Conquer,Quickselect,Sorting,Heap (Priority Queue)	Medium
1986	Minimum Number of Work Sessions to Finish the Tasks	Bit Manipulation,Array,Dynamic Programming,Backtracking,Bitmask	Medium
1987	Number of Unique Good Subsequences	String,Dynamic Programming	Hard
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	🔒
2006	Count Number of Pairs With Absolute Difference K		Easy
2007	Find Original Array From Doubled Array		Medium
2008	Maximum Earnings From Taxi		Medium
2009	Minimum Number of Operations to Make Array Continuous		Hard
2010	The Number of Seniors and Juniors to Join the Company II		Hard	🔒
2011	Final Value of Variable After Performing Operations		Easy
2012	Sum of Beauty in the Array		Medium
2013	Detect Squares		Medium
2014	Longest Subsequence Repeated k Times		Hard

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