[LeetCode] 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.) Exampl
[LeetCode] 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
[LeetCode] 209. Minimum Size Subarray Sum
Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. If there is no such subarray, return 0 ins
[LeetCode] 159. Longest Substring with At Most Two Distinct Characters
Given a string s, return the length of the longest substring that contains at most two distinct characters. Example 1:Input: s = “eceba”Output: 3Explanation: The substring is “ece” which its leng
[LeetCode] 340. Longest Substring with At Most K Distinct Characters
Given a string s and an integer k, return the length of the longest substring of s that contains at most k distinct characters. Example 1:Input: s = “eceba”, k = 2Output: 3Explanation: The s
[LeetCode] 3. Longest Substring Without Repeating Characters
Given a string s, find the length of the longest substring without repeating characters. Example 1:Input: s = “abcabcbb”Output: 3Explanation: The answer is “abc”, with the length of 3. Example 2:
[LeetCode] 76. Minimum Window Substring
Given two strings s and t of lengths m and n respectively, return the minimum windowsubstring of s such that every character in t (including duplicates) is included in the window. If there is no such
[LeetCode] 419. Battleships in a Board
Given an m x n matrix board where each cell is a battleship ‘X’ or empty ‘.’, return the number of the battleships on board. Battleships can only be placed horizontally or vertically on board. In othe