题目 A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' i…

题目 Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the grid. For example, There is one obstacle in the mi…

62. Unique Paths A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (mar…

Medium! 题目描述: 一个机器人位于一个 m x n 网格的左上角 (起始点在下图中标记为“Start” ). 机器人每次只能向下或者向右移动一步.机器人试图达到网格的右下角(在下图中标记为“Finish”). 问总共有多少条不同的路径? 例如,上图是一个7 x 3 的网格.有多少可能的路径? 说明:m 和 n 的值均不超过 100. 示例 1: 输入: m = 3, n = 2 输出: 3 解释: 从左上角开始,总共有 3 条路径可以到达右下角. 1. 向右 -> 向右 -> 向下 2…

题目 Given n, how many structurally unique BST's (binary search trees) that store values 1-n? For example, Given n = 3, there are a total of 5 unique BST's. 分析 此题与上题本质相同,LeetCode 95 Unique Binary Search Trees要求得到全部二叉查找树,打印其层序遍历序列. 而此题,只要求元素 [1,n] 能构成的二…

题目 Given n, generate all structurally unique BST's (binary search trees) that store values 1-n. For example, Given n = 3, your program should return all 5 unique BST's shown below. confused what "{1,#,2,3}" means? > read more on how binary tr…

题目如下: Python代码: def numTrees(self, n): """ :type n: int :rtype: int """ num=[0]*(n+1) num[0]=num[1]=1 for i in range(2,n+1): for j in range(i): num[i] += num[j]*num[i-j-1] return num[n]…

题目 Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…

Home / Qt 学习之路 2 / Qt 学习之路 2(62):保存 XML Qt 学习之路 2(62):保存 XML  豆子  2013年8月26日  Qt 学习之路 2  9条评论 前面几章我们讨论了读取 XML 文档的三种方法.虽然各有千秋,但是 Qt 推荐的是使用QXmlStreamReader.与此同时,许多应用程序不仅需要读取 XML,还需要写入 XML.为此,Qt 同样提供了三种方法: 使用QXmlStreamWriter: 构造一个 DOM 树,然后掉其save()函数: 使用…

题目 Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm? 分析 同LeetCode(274)H-Index第二个版本,给定引用数量序列为递增的:这就省略了我们的第一个排序步骤: O(n)的时间复杂度,遍历一次即可. AC代码 class Solution { public: int hIndex(vector<int>…