Image Overlap Two images A and B are given, represented as binary, square matrices of the same size.  (A binary matrix has only 0s and 1s as values.) We translate one image however we choose (sliding it left, right, up, or down any number of units),…

Rectangle Overlap A rectangle is represented as a list [x1, y1, x2, y2], where (x1, y1) are the coordinates of its bottom-left corner, and (x2, y2) are the coordinates of its top-right corner. Two rectangles overlap if the area of their intersection…

Find And Replace in String To some string S, we will perform some replacement operations that replace groups of letters with new ones (not necessarily the same size). Each replacement operation has 3 parameters: a starting index i, a source word x an…

Sum of Distances in Tree An undirected, connected tree with N nodes labelled 0...N-1 and N-1 edges are given. The ith edge connects nodes edges[i][0] and edges[i][1] together. Return a list ans, where ans[i] is the sum of the distances between node i…

Flipping an Image Given a binary matrix A, we want to flip the image horizontally, then invert it, and return the resulting image. To flip an image horizontally means that each row of the image is reversed.  For example, flipping [1, 1, 0] horizontal…

LeetCode Weekly Contest 8 415. Add Strings User Accepted: 765 User Tried: 822 Total Accepted: 789 Total Submissions: 1844 Difficulty: Easy Given two non-negative numbers num1 and num2 represented as string, return the sum of num1 and num2. Note: The…

Weekly Contest 86 A:840. 矩阵中的幻方 3 x 3 的幻方是一个填充有从 1 到 9 的不同数字的 3 x 3 矩阵,其中每行,每列以及两条对角线上的各数之和都相等. 给定一个由整数组成的 N × N 矩阵,其中有多少个 3 × 3 的 “幻方” 子矩阵?(每个子矩阵都是连续的). 直接模拟即可,本来是签到题,由于粗心,浪费了时间. class Solution { public: int numMagicSquaresInside(vector<vector<int&…

leetcode weekly contest 43 leetcode649. Dota2 Senate leetcode649.Dota2 Senate 思路: 模拟规则round by round. class Solution { public: string predictPartyVictory(string senate) { int len = senate.size(); int r = 0; int d = 0; int i = 0; while(1) { if(senate[…

LeetCode Weekly Contest 23 1. Reverse String II Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them.…

第一题:柠檬水找零 问题: 在柠檬水摊上,每一杯柠檬水的售价为 5 美元. 顾客排队购买你的产品,(按账单 bills 支付的顺序)一次购买一杯. 每位顾客只买一杯柠檬水,然后向你付 5 美元.10 美元或 20 美元.你必须给每个顾客正确找零,也就是说净交易是每位顾客向你支付 5 美元. 注意,一开始你手头没有任何零钱. 如果你能给每位顾客正确找零,返回 true ,否则返回 false . 示例 1: 输入:[5,5,5,10,20] 输出:true 解释: 前 3 位顾客那里,我们按顺序收…