LeetCode 64. Minimum Path Sum

class Solution {
public:
    int minPathSum(vector<vector<int>>& grid) {
        int n=grid.size();
        int m=grid[0].size();
        int dp[n+1][m+1];
        memset(dp,0,sizeof(dp));
        dp[0][0]=grid[0][0];
        for(int i=1;i<m;i++)
         dp[0][i]=dp[0][i-1]+grid[0][i];
         for(int i=1;i<n;i++){
             dp[i][0]+=dp[i-1][0]+grid[i][0];
         }
         for(int i=1;i<n;i++){
             for(int j=1;j<m;j++){
                 dp[i][j]=min(dp[i-1][j],dp[i][j-1])+grid[i][j];
             }
         }
         return dp[n-1][m-1];
    }
};