Geeksforgeeks Solution For " Diagonal sum "

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Problem :- Given a square matrix of size M×M . Your task is to calculate the sum of its diagonals.

Input:
The first line of input contains an integer T denoting the number of test cases. Then T test cases follow. First line of each test case contains a single integer M denoting the size of the square matrix. The next  line contains M*M space separated values of the matrix A.

Output:
For each test case in a new line print the sum of diagonals of the matrix.

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Solution :-

#include <bits/stdc++.h>
using namespace std;
int main()
{
int T;
cin>>T;
while(T--)
{
    int i,j,n,sum=0;
    cin>>n;
    int ar[n][n];
    for(i=0;i<n;i++)
    for(j=0;j<n;j++)
    cin>>ar[i][j];
    
    for(i=0;i<n;i++)
    {
        for(j=0;j<n;j++)
        {
            if(i==j)
            sum+=ar[i][j];
            if((i+j)==(n-1))
            sum+=ar[i][j];
        }
    }
    cout<<sum<<endl;
}
return 0;

}

Output :-