题目描述

题目难度：Medium
Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.

• Example:

Input:
[
[1,3,1],
[1,5,1],
[4,2,1]
]
Output: 7
Explanation: Because the path 1→3→1→1→1 minimizes the sum.

AC代码

class Solution {
    public int minPathSum(int[][] grid) {
        int m = grid.length;
        int n = grid[0].length;
        for(int i = 1;i < m;i++) grid[i][0] += grid[i - 1][0];
        for(int i = 1;i < n;i++) grid[0][i] += grid[0][i - 1];
        for(int i = 1; i < m; i++){
            for(int j = 1; j < n; j++){
                grid[i][j] += Math.min(grid[i - 1][j], grid[i][j - 1]); 
            }
        }
        
        return grid[m - 1][n - 1];
    }
}