Author: devangini123

🌙 Problem Statement 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 digits to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters. source: leetcode image 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

🌙 Problem Statement: Find all valid combinations of k numbers that sum up to n such that the following conditions are true: Only numbers 1 through 9 are used. Each number is used at most once. Return a list of all possible valid combinations. The list must not contain the same combination twice, and the combinations may be returned in any order. Example 1: Input: k = 3, n = 7 Output: [[1, 2, 4]] Explanation: 1 + 2 + 4 = 7 There are no other valid combinations. Example 2: Input: k = 3, n = 9 Output: [[1,2,6],[1,3,5],[2,3,4]]…

🌙 Problem Statement: Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target. Each number in candidates may only be used once in the combination. Note: The solution set must not contain duplicate combinations. Example 1: Input: candidates = [10,1,2,7,6,1,5], target = 8 Output: [ [1,1,6], [1,2,5], [1,7], [2,6] ] Example 2: Input: candidates = [2,5,2,1,2], target = 5 Output: [ [1,2,2], [5] ] Constraints: 1

🌙 Problem Statement: Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order. The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different. The test cases are generated such that the number of unique combinations that sum up to target is less than 150 combinations for the given input. Example 1: Input: candidates =…

🌙 Problem Statement: Given an integer array nums that may contain duplicates, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order. Example 1: Input:nums = [1,2,2] Output: [[],[1],[1,2],[1,2,2],[2],[2,2]] Example 2: Input: nums = [0] Output:[[],[0]] Constraints: 1 start && arr[i-1] === arr[i] → TRUE (skip duplicate) Loop ends path.pop() → path = [] Loop i = 1 → arr[1] = 2 path.push(2) → path = [2] Call backtrack([2], 2) → Push [2] → result = […, [2]] Loop i = 2 → arr[2] = 2 Condition: i >…

🌙 Problem Statement: Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. Example 1: Input:nums = [1,2,3] Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]] Example 2: Input: nums = [0,1] Output:[[0,1],[1,0]] Example 3: Input: nums = [1] Output:[[1]] Constraints: 1

🌙 Problem Statement: Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n]. You may return the answer in any order. Example 1: Input: n = 4, k = 2 Output: [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] Explanation: There are 4 choose 2 = 6 total combinations. Note that combinations are unordered, i.e., [1,2] and [2,1] are considered to be the same combination. Example 2: Input: n = 1, k = 1 Output:[[1]] Explanation: There is 1 choose 1 = 1 total combination. Constraints: 1

🌙 Problem Statement: Given an integer array nums of unique elements, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order. Example 1: Input: nums = [1,2,3] Output:[[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]] Example 2: Input: nums = [0] Output:[[],[0]] Constraints: 1

🌙 Priority Queue Code Sorting Code In the LeetCode environment, Javascript developers have access to a built-in priority queue feature. Code: Sorting class PriorityQueue { constructor() { this.queue = []; } // enqueue: Push the Value enqueue(value, priority) { this.queue.push({ value, priority }); this.queue.sort((a, b) => b.priority – a.priority); //Highest Priority first } // dequeue: Remove the Value dequeue() { return this.queue.shift(); // Remove the first item (highest priority) } peek() { return this.queue[0]; } isEmpty() { return this.queue.length === 0; } } // Demo const pq = new PriorityQueue(); pq.enqueue(“Fever”, 1); pq.enqueue(“Accident”, 5); pq.enqueue(“Headache”, 3); console.log(pq.dequeue()); // Accident (priority…

🌙 Problem Statement: You are given an array of integers stones where stones[i] is the weight of the ith stone. We are playing a game with the stones. On each turn, we choose the heaviest two stones and smash them together. Suppose the heaviest two stones have weights x and y with x