把字符串转换成整数 class Solution { public: int StrToInt(string str) { int n = str.size(), s = 1; long long res = 0; if(!n) return 0; if(str[0] == '-') s = -1; for(int i = (str[0] == '-' || str[0] == '+') ? 1 : 0; i < n; ++i){ if(!('0' <= str[i] && s…

leetcode 39 先排序,然后dfs 注意先整全局变量可以减少空间利用 class Solution { vector<vector<int>>ret; vector<int>temp; vector<int> srt; public: vector<vector<int>> combinationSum(vector<int>& candidates, int target) { srt=candidate…

Web前端性能优化WPO,相信大多数前端同学都不会陌生,在各自所负责的站点页面中,也都会或多或少的有过一定的技术实践.可以说,这个领域并不缺乏成熟技术理论和技术牛人:例如Yahoo的web站点性能优化黄金法则,以及大名鼎鼎的优化大师Steve Souders.本文并非一篇讨论性能优化技术方法的文章,而更多的是对中文站搜索List页面持续两年多的前端性能优化实践的思路总结.希望对正在从事这个领域研究的前端同学能有所帮助. 简单的说,我们的性能优化实践分为三个阶段:初探期.立规期.创新期, 每个阶段…

最短路径=>BFS    所有路径=>DFS 126. Word Ladder II BFS+DFS: BFS找出下一个有效的word进队 并记录step 更新两个变量:unordered_map<string, vector<string>> next, unordered_map<string,int> visit DFS找出所有的解法 更新两个变量:vector<vector<string>> result, vector<…

Given two binary trees, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical and the nodes have the same value. Example 1: Input: 1 1 / \ / \ 2 3 2 3 [1,2,3], [1,2,3] Outpu…

Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. Note: A leaf is a node with no children. Example: Given binary tree [3,9,20,null,null,15,7…

Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. Note: A leaf is a node with no children. Example: Given binary tree [3,9,20,null,null,15,7…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

代码: 个人浅薄的认为DFS就是回溯法中的一种,一般想到用DFS我们脑中一般都有一颗解法树,然后去按照深度优先搜索去寻找解.而分支界限法则不算是回溯,无论其是采用队列形式的还是优先队列形式的分支界限法. 下面这个函数就是我的DFS的函数,先介绍一下参数的含义,index表示当前要判断是否合适的candidates中的元素的下标,t表示即将要把新数据加入的位置. void backTrace(int sum, int target, int a[], int index, int t, vecto…

这是悦乐书的第335次更新,第360篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第205题(顺位题号是874).网格上的机器人从点(0,0)开始并朝北.机器人可以接收三种可能类型的命令之一: -2:向左转90度. -1:向右转90度. 1 <= x <= 9:向前移动x个单位. 一些网格方块是障碍物.第i个障碍位于网格点(obstacles[i][0],obstacles[i][1]).如果机器人遇到障碍点,机器人将停留在障碍点前一个网格方格上(但仍然会继续执行…