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leetcode:Minimum Path Sum(路线上元素和的最小值)

题目:
 
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.
 
题意从左上到右下,所有可能的路径中,求经过的元素和最小值。
动态规划基础题了,dp每个状态由左边或者上边的值中,较小的值与当前状态的值相加得到。
 
注意考虑边界情况就行了。
 
 
 
int dp[1000][1000];  
class Solution {  
public:  
    int minPathSum(vector<vector<int> > &grid) {  
        int rows=grid.size();  
        if(rows==0)return 0;  
        int cols=grid[0].size();  
        if(cols==0)return 0;  
        memset(dp,0,sizeof(dp));  
        for(int i=0;i<rows;++i)  
        {  
            for(int j=0;j<cols;++j)  
            {                 
                if(i==0&&j==0)dp[0][0]=grid[0][0];  
                else if(j==0)dp[i][0]=dp[i-1][0]+grid[i][0];  
                else if(i==0)dp[0][j]=dp[0][j-1]+grid[0][j];  
                else dp[i][j]=min(dp[i-1][j],dp[i][j-1])+grid[i][j];  
            }  
        }  
        return dp[rows-1][cols-1];          
    }  
};  

 

 
 
补充:软件开发 , C++ ,
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