Min Cost Path-dynamic programming

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.

example:

n=3,m=3;

a=[

    [1,3,1],

    [1,5,1],

    [4,2,1]

    ]

Output: 7

Explanation: Because the path 1→3→1→1→1 minimizes the sum.

lets use dynamic programming to solve this question:

c++ implementation:

t is the no.of test cases:

#include <iostream>
#include <bits/stdc++.h>
using namespace std;

int main() { int t; cin>>t;
while(t--)
{ 
    int n; cin>>n;
    int m;cin>>m;
   int a[n][m];

for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
cin>>a[i][j];

    if (m == 0||n==0) return 0;
     
 
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (i > 0 && j > 0) {
                    a[i][j] += min(a[i - 1][j], a[i][j - 1]);
                } else if (i > 0) {
                    a[i][j] += a[i - 1][j];
                } else if (j > 0) {
                    a[i][j] += a[i][j - 1];
                }
            }
        }
        cout<< a[n - 1][m - 1];


cout<<endl;   
}
 //code
 return 0;
}