Leetcode 64. Minimum Path Sum 最小路径和 解题报告

1 解题思想

嗯，我做的时候是乱序，写的时候才发现，这完全就是和62 63一个德行啊，做法还是基本一样，不同的是，62 63是求和，64这里是取每一步的最小和。

标准的动态规划，至于怎么走，请看62 63：
Unique Paths 路径搜寻 解题报告
Unique Paths II 路径搜寻2 解题报告

2 原题

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.

3 AC解

public class Solution {
    /**
     * 很标准的动态规划的题目
     * */
    public int minPathSum(int[][] grid) {
        if(grid.length==0 || grid[0].length==0)
            return 0;
        int m=grid.length;
        int n=grid[0].length;
        int dp[][]=new int[m][n];
        int top,left;
        int i=0,j;
        dp[0][0]=grid[0][0];
        for( j=1;j1]+grid[i][j];
        }
         for( j=1;j1][i]+grid[j][i];
        }
        for( i=1;ifor( j=1;j1][j];
                left=dp[i][j-1];
                dp[i][j]=Math.min(top,left)+grid[i][j];
            }
        }
        return dp[m-1][n-1];
    }
}