Added tasks 11-25

src/main/ts/g0001_0100/s0011_container_with_most_water/readme.md

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+[![](https://img.shields.io/github/stars/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Stars&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript)
+[![](https://img.shields.io/github/forks/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript/fork)
+
+## 11\. Container With Most Water
+
+Medium
+
+Given `n` non-negative integers <code>a<sub>1</sub>, a<sub>2</sub>, ..., a<sub>n</sub></code> , where each represents a point at coordinate <code>(i, a<sub>i</sub>)</code>. `n` vertical lines are drawn such that the two endpoints of the line `i` is at <code>(i, a<sub>i</sub>)</code> and `(i, 0)`. Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.
+
+**Notice** that you may not slant the container.
+
+**Example 1:**
+
+![](https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/17/question_11.jpg)
+
+**Input:** height = [1,8,6,2,5,4,8,3,7]
+
+**Output:** 49
+
+**Explanation:** The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49. 
+
+**Example 2:**
+
+**Input:** height = [1,1]
+
+**Output:** 1 
+
+**Example 3:**
+
+**Input:** height = [4,3,2,1,4]
+
+**Output:** 16 
+
+**Example 4:**
+
+**Input:** height = [1,2,1]
+
+**Output:** 2 
+
+**Constraints:**
+
+*   `n == height.length`
+*   <code>2 <= n <= 10<sup>5</sup></code>
+*   <code>0 <= height[i] <= 10<sup>4</sup></code>
+
+## Solution
+
+```typescript
+function maxArea(height: number[]): number {
+    let maxArea = -1
+    let left = 0
+    let right = height.length - 1
+    while (left < right) {
+        if (height[left] < height[right]) {
+            maxArea = Math.max(maxArea, height[left] * (right - left))
+            left++
+        } else {
+            maxArea = Math.max(maxArea, height[right] * (right - left))
+            right--
+        }
+    }
+    return maxArea
+}
+
+export { maxArea }
+```

src/main/ts/g0001_0100/s0015_3sum/readme.md

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+[![](https://img.shields.io/github/stars/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Stars&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript)
+[![](https://img.shields.io/github/forks/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript/fork)
+
+## 15\. 3Sum
+
+Medium
+
+Given an integer array nums, return all the triplets `[nums[i], nums[j], nums[k]]` such that `i != j`, `i != k`, and `j != k`, and `nums[i] + nums[j] + nums[k] == 0`.
+
+Notice that the solution set must not contain duplicate triplets.
+
+**Example 1:**
+
+**Input:** nums = [-1,0,1,2,-1,-4]
+
+**Output:** [[-1,-1,2],[-1,0,1]] 
+
+**Example 2:**
+
+**Input:** nums = []
+
+**Output:** [] 
+
+**Example 3:**
+
+**Input:** nums = [0]
+
+**Output:** [] 
+
+**Constraints:**
+
+*   `0 <= nums.length <= 3000`
+*   <code>-10<sup>5</sup> <= nums[i] <= 10<sup>5</sup></code>
+
+## Solution
+
+```typescript
+function threeSum(nums: number[]): number[][] { //NOSONAR
+    nums.sort((a, b) => a - b)
+    const len = nums.length
+    const result: number[][] = []
+    let l: number
+    let r: number
+    for (let i = 0; i < len - 2; i++) {
+        l = i + 1
+        r = len - 1
+        while (r > l) {
+            const sum = nums[i] + nums[l] + nums[r]
+            if (sum < 0) {
+                l++
+            } else if (sum > 0) {
+                r--
+            } else {
+                const list: number[] = [nums[i], nums[l], nums[r]]
+                result.push(list)
+                while (l < r && nums[l + 1] === nums[l]) {
+                    l++
+                }
+                while (r > l && nums[r - 1] === nums[r]) {
+                    r--
+                }
+                l++
+                r--
+            }
+        }
+        while (i < len - 1 && nums[i + 1] === nums[i]) {
+            i++ //NOSONAR
+        }
+    }
+    return result
+}
+
+export { threeSum }
+```

src/main/ts/g0001_0100/s0017_letter_combinations_of_a_phone_number/readme.md

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+[![](https://img.shields.io/github/stars/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Stars&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript)
+[![](https://img.shields.io/github/forks/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript/fork)
+
+## 17\. Letter Combinations of a Phone Number
+
+Medium
+
+Given a string containing digits from `2-9` inclusive, return all possible letter combinations that the number could represent. Return the answer in **any order**.
+
+A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.
+
+![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Telephone-keypad2.svg/200px-Telephone-keypad2.svg.png)
+
+**Example 1:**
+
+**Input:** digits = "23"
+
+**Output:** ["ad","ae","af","bd","be","bf","cd","ce","cf"] 
+
+**Example 2:**
+
+**Input:** digits = ""
+
+**Output:** [] 
+
+**Example 3:**
+
+**Input:** digits = "2"
+
+**Output:** ["a","b","c"] 
+
+**Constraints:**
+
+*   `0 <= digits.length <= 4`
+*   `digits[i]` is a digit in the range `['2', '9']`.
+
+## Solution
+
+```typescript
+function letterCombinations(digits: string): string[] {
+    if (digits.length === 0) {
+        return []
+    }
+    const letters: string[] = ['', '', 'abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz']
+    const ans: string[] = []
+    const sb: string[] = []
+    findCombinations(0, digits, letters, sb, ans)
+    return ans
+}
+
+function findCombinations(start: number, nums: string, letters: string[], curr: string[], ans: string[]): void {
+    if (curr.length === nums.length) {
+        ans.push(curr.join(''))
+        return
+    }
+    for (let i = start; i < nums.length; i++) {
+        const n = parseInt(nums.charAt(i))
+        for (let j = 0; j < letters[n].length; j++) {
+            const ch = letters[n].charAt(j)
+            curr.push(ch)
+            findCombinations(i + 1, nums, letters, curr, ans)
+            curr.pop()
+        }
+    }
+}
+
+export { letterCombinations }
+```

src/main/ts/g0001_0100/s0019_remove_nth_node_from_end_of_list/readme.md

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+[![](https://img.shields.io/github/stars/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Stars&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript)
+[![](https://img.shields.io/github/forks/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript/fork)
+
+## 19\. Remove Nth Node From End of List
+
+Medium
+
+Given the `head` of a linked list, remove the `nth` node from the end of the list and return its head.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/10/03/remove_ex1.jpg)
+
+**Input:** head = [1,2,3,4,5], n = 2
+
+**Output:** [1,2,3,5] 
+
+**Example 2:**
+
+**Input:** head = [1], n = 1
+
+**Output:** [] 
+
+**Example 3:**
+
+**Input:** head = [1,2], n = 1
+
+**Output:** [1] 
+
+**Constraints:**
+
+*   The number of nodes in the list is `sz`.
+*   `1 <= sz <= 30`
+*   `0 <= Node.val <= 100`
+*   `1 <= n <= sz`
+
+**Follow up:** Could you do this in one pass?
+
+## Solution
+
+```typescript
+import { ListNode } from '../../com_github_leetcode/listnode'
+
+let localN: number
+
+function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
+    localN = n
+    const dummy = new ListNode(0)
+    dummy.next = head
+    removeNth(dummy)
+    return dummy.next
+}
+
+function removeNth(node: ListNode | null): void {
+    if (!node || !node.next) { //NOSONAR
+        return
+    }
+    removeNth(node.next)
+    localN--
+
+    if (localN === 0) {
+        node.next = node.next?.next || null //NOSONAR
+    }
+}
+
+export { removeNthFromEnd }
+```

src/main/ts/g0001_0100/s0020_valid_parentheses/readme.md

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+[![](https://img.shields.io/github/stars/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Stars&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript)
+[![](https://img.shields.io/github/forks/LeetCode-in-TypeScript/LeetCode-in-TypeScript?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-TypeScript/LeetCode-in-TypeScript/fork)
+
+## 20\. Valid Parentheses
+
+Easy
+
+Given a string `s` containing just the characters `'('`, `')'`, `'{'`, `'}'`, `'['` and `']'`, determine if the input string is valid.
+
+An input string is valid if:
+
+1.  Open brackets must be closed by the same type of brackets.
+2.  Open brackets must be closed in the correct order.
+
+**Example 1:**
+
+**Input:** s = "()"
+
+**Output:** true 
+
+**Example 2:**
+
+**Input:** s = "()[]{}"
+
+**Output:** true 
+
+**Example 3:**
+
+**Input:** s = "(]"
+
+**Output:** false 
+
+**Example 4:**
+
+**Input:** s = "([)]"
+
+**Output:** false 
+
+**Example 5:**
+
+**Input:** s = "{[]}"
+
+**Output:** true 
+
+**Constraints:**
+
+*   <code>1 <= s.length <= 10<sup>4</sup></code>
+*   `s` consists of parentheses only `'()[]{}'`.
+
+## Solution
+
+```typescript
+function isValid(s: string): boolean {
+    const stack: string[] = []
+    for (let i = 0; i < s.length; i++) {
+        const c = s.charAt(i)
+        if (c === '(' || c === '[' || c === '{') {
+            stack.push(c)
+        } else if (
+            (c === ')' && stack.length > 0 && stack[stack.length - 1] === '(') ||
+            (c === '}' && stack.length > 0 && stack[stack.length - 1] === '{') ||
+            (c === ']' && stack.length > 0 && stack[stack.length - 1] === '[')
+        ) {
+            stack.pop()
+        } else {
+            return false
+        }
+    }
+    return stack.length === 0
+}
+
+export { isValid }
+```