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424. Longest Repeating Character Replacement You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most k times. Return the length of the longest substring containing the same letter you can get after performing the above operations. 1 2 3 4 5 6 7 8 9 10 11 12 Example 1: Input: s = "ABAB", k = 2 Output: 4 Explanation: Replace the two 'A's with two 'B's or vice versa....

1625. Lexicographically Smallest String After Applying Operations You are given a string s of even length consisting of digits from 0 to 9, and two integers a and b. You can apply either of the following two operations any number of times and in any order on s: Add a to all odd indices of s (0-indexed). Digits post 9 are cycled back to 0. For example, if s = “3456” and a = 5, s becomes “3951”....

24. Swap Nodes in Pairs Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list’s nodes (i.e., only nodes themselves may be changed.) 1 2 3 4 Example 1: Input: head = [1,2,3,4] Output: [2,1,4,3] 1 2 3 4 5 6 7 8 9 Example 2: Input: head = [] Output: [] Example 3: Input: head = [1] Output: [1] Constraints:...

1099. Two Sum Less Than K Given an array nums of integers and integer k, return the maximum sum such that there exists i < j with nums[i] + nums[j] = sum and sum < k. If no i, j exist satisfying this equation, return -1. 1 2 3 4 5 6 7 8 9 10 11 Example 1: Input: nums = [34,23,1,24,75,33,54,8], k = 60 Output: 58 Explanation: We can use 34 and 24 to sum 58 which is less than 60....

19. Remove Nth Node From End of List Given the head of a linked list, remove the nth node from the end of the list and return its head. 1 2 3 4 Example 1: Input: head = [1,2,3,4,5], n = 2 Output: [1,2,3,5] 1 2 3 4 5 6 7 8 9 Example 2: Input: head = [1], n = 1 Output: [] Example 3: Input: head = [1,2], n = 1 Output: [1] Constraints:...

2. Add Two Numbers You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list. You may assume the two numbers do not contain any leading zero, except the number 0 itself. 1 2 3 4 5 Example 1: Input: l1 = [2,4,3], l2 = [5,6,4] Output: [7,0,8] Explanation: 342 + 465 = 807....

523. Continuous Subarray Sum Given an integer array nums and an integer k, return true if nums has a continuous subarray of size at least two whose elements sum up to a multiple of k, or false otherwise. An integer x is a multiple of k if there exists an integer n such that x = n * k. 0 is always a multiple of k. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Example 1: Input: nums = [23,2,4,6,7], k = 6 Output: true Explanation: [2, 4] is a continuous subarray of size 2 whose elements sum up to 6....

974. Subarray Sums Divisible by K Given an array nums of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by k. 1 2 3 4 5 6 Example 1: Input: nums = [4,5,0,-2,-3,1], k = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by k = 5: [4, 5, 0, -2, -3, 1], [5], [5, 0], [5, 0, -2, -3], [0], [0, -2, -3], [-2, -3] Note:...

1898. Maximum Number of Removable Characters You are given two strings s and p where p is a subsequence of s. You are also given a distinct 0-indexed integer array removable containing a subset of indices of s (s is also 0-indexed). You want to choose an integer k (0 <= k <= removable.length) such that, after removing k characters from s using the first k indices in removable, p is still a subsequence of s....

1899. Merge Triplets to Form Target Triplet A triplet is an array of three integers. You are given a 2D integer array triplets, where triplets[i] = [ai, bi, ci] describes the ith triplet. You are also given an integer array target = [x, y, z] that describes the triplet you want to obtain. To obtain target, you may apply the following operation on triplets any number of times (possibly zero):...

31. Next Permutation Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such an arrangement is not possible, it must rearrange it as the lowest possible order (i.e., sorted in ascending order). The replacement must be in place and use only constant extra memory. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Example 1: Input: nums = [1,2,3] Output: [1,3,2] Example 2: Input: nums = [3,2,1] Output: [1,2,3] Example 3: Input: nums = [1,1,5] Output: [1,5,1] Example 4: Input: nums = [1] Output: [1] Constraints:...

137. Single Number II Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it. You must implement a solution with a linear runtime complexity and use only constant extra space. 1 2 3 4 5 6 7 8 9 Example 1: Input: nums = [2,2,3,2] Output: 3 Example 2: Input: nums = [0,1,0,1,0,1,99] Output: 99 Constraints:...

260. Single Number III Given an integer array nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. You can return the answer in any order. You must write an algorithm that runs in linear runtime complexity and uses only constant extra space. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Example 1: Input: nums = [1,2,1,3,2,5] Output: [3,5] Explanation: [5, 3] is also a valid answer....

244. Shortest Word Distance II Design a data structure that will be initialized with a string array, and then it should answer queries of the shortest distance between two different strings from the array. Implement the WordDistance class: WordDistance(String[] wordsDict) initializes the object with the strings array wordsDict. int shortest(String word1, String word2) returns the shortest distance between word1 and word2 in the array wordsDict. 1 2 3 4 5 6 7 8 9 10 11 12 Example 1: Input ["WordDistance", "shortest", "shortest"] [[["practice", "makes", "perfect", "coding", "makes"]], ["coding", "practice"], ["makes", "coding"]] Output [null, 3, 1] Explanation WordDistance wordDistance = new WordDistance(["practice", "makes", "perfect", "coding", "makes"]); wordDistance....

245. Shortest Word Distance III Given an array of strings wordsDict and two strings that already exist in the array word1 and word2, return the shortest distance between these two words in the list. Note that word1 and word2 may be the same. It is guaranteed that they represent two individual words in the list. 1 2 3 4 5 6 7 8 9 Example 1: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "coding" Output: 1 Example 2: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "makes" Output: 3 Constraints:...