[LeetCode] 130. Surrounded Regions
You are given an m x n matrix board containing letters ‘X’ and ‘O’, capture regions that are surrounded: Connect: A cell is connected to adjacent cells horizontally or vertically.Region: To form a reg
[LeetCode] 1095. Find in Mountain Array
(This problem is an interactive problem.) You may recall that an array arr is a mountain array if and only if: arr.length >= 3There exists some i with 0 < i < arr.length - 1 such that:ar
[LeetCode] 704. Binary Search
Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1. You
[LeetCode] 221. Maximal Square
Given an m x n binary matrix filled with 0’s and 1’s, find the largest square containing only 1’s and return its area. Example 1: Input: matrix = [[“1”,”0”,”1”,”0”,”0”],[“1”,”0”,”1”,”1”,”1”],[“1”
[LeetCode] 621. Task Scheduler
You are given an array of CPU tasks, each represented by letters A to Z, and a cooling time, n. Each cycle or interval allows the completion of one task. Tasks can be completed in any order, but there
[LeetCode] 18. 4Sum
Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:0 <= a, b, c, d < na, b, c, and d are distinct.nums[a] + nums
[LeetCode] 380. Insert Delete GetRandom O(1)
Design a data structure that supports all following operations in average O(1) time. insert(val): Inserts an item val to the set if not already present.remove(val): Removes an item val from the set if
[LeetCode] 80. Remove Duplicates from Sorted Array II
Given an integer array nums sorted in non-decreasing order, remove some duplicates in-place such that each unique element appears at most twice. The relative order of the elements should be kept the s