Minimum Path Sum -- Leetcode

Question:

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.

Answer:

class Solution {

public:

    int minPathSum(vector<vector<int> > &grid) {

        int m=grid.size();

        int n=grid[0].size();

        if(m==0||n==0) return -1;

        

        int dp[m][n];

        memset(dp,0,sizeof(dp));

        dp[0][0]=grid[0][0];

        for(int i=1;i<m;++i){

            dp[i][0]=dp[i-1][0]+grid[i][0];

        }

        for(int j=1;j<n;++j){

            dp[0][j]=dp[0][j-1]+grid[0][j];

        }

        for(int i=1;i<m;++i){

            for(int j=1;j<n;++j){

                dp[i][j]=grid[i][j]+min(dp[i-1][j],dp[i][j-1]);

            }

        }

        return dp[m-1][n-1];

    }

};