62. Unique Paths My Submissions Question Total Accepted: 75227 Total Submissions: 214539 Difficulty: Medium 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…

Leetcode之动态规划(DP)专题-63. 不同路径 II(Unique Paths II) 初级题目:Leetcode之动态规划(DP)专题-62. 不同路径(Unique Paths) 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”). 现在考虑网格中有障碍物.那么从左上角到右下角将会有多少条不同的路径? 网格中的障碍物和空位置分别用 1 和 0 来表…

LeetCode:零钱兑换[322][DP] 题目描述 给定不同面额的硬币 coins 和一个总金额 amount.编写一个函数来计算可以凑成总金额所需的最少的硬币个数.如果没有任何一种硬币组合能组成总金额,返回 -1. 示例 1: 输入: coins = [1, 2, 5], amount = 11 输出: 3 解释: 11 = 5 + 5 + 1 示例 2: 输入: coins = [2], amount = 3 输出: -1 说明:你可以认为每种硬币的数量是无限的. 题目分析 很显然,这是…

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…

class Solution { public: int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) { || obstacleGrid[].size()==) ; ].size(); ][n-]==) ; vector<vector<int> > dp(m); ;i<dp.size();++i) dp[i].resize(n); ;i<dp.size();++i…

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 middl…

判断一个物体从左上角到右下角有多少种走法 class Solution(object): def uniquePaths(self, m, n): flag = [[1 for j in range(n)] for i in range(m)] for i in range(1,m): for j in range(1,n): flag[i][j] = flag[i-1][j] + flag[i][j-1] return flag[-1][-1]…

一个m*n的表格,每个格子有一个非负数,求从左上到右下最短的路径值 和62,63两个值是同一个思路,建立dp表,记录每个位置到右下角的最短路径的值 class Solution(object): def minPathSum(self, grid): m,n = len(grid),len(grid[0]) flag = [[0 for i in range(n)] for j in range(m)] flag[m-1][n-1] = grid[m-1][n-1] for i in range…

https://leetcode.com/problems/k-inverse-pairs-array/description/ [题意] 给定n和k,求正好有k个逆序对的长度为n的序列有多少个,0<=k<=1000, 1<=n<=1000,答案模1e9+7 [思路] dp[i][j]表示正好有j个逆序对的长度为i的序列的方案数,最终我们要求的就是dp[n][k] 考虑dp[i+1][j]和dp[i][j]的关系,长度为i+1的序列相当于在长度为i的序列中插入一个数,那么有 xxx…

https://leetcode.com/problems/palindrome-partitioning-ii/description/ [题意] 给定一个字符串,求最少切割多少下,使得切割后的每个子串都是回文串 [思路] 求一个字符串的所有子串是否是回文串,O(n^2) dp从后往前推 vector<vector<bool> > p(len,vector<bool>(len)); ;i<len-;i++){ ;j<len-;j++){ if(j!=i)…