Envío 2007

Código

#include <iostream>
using namespace std;

int main(void)
{
    long length, hr, vr, ld = 0, rd = 0, bf = 0;
    bool isMagic = true;

    cin >> length;
    int arr[length][length];

    for (long i = 0; i < length; i++)
    {
        for (long j = 0; j < length; j++)
            cin >> arr[i][j];
    }

    for (long i = 0; i < length; i++)
    {
        hr = 0;
        vr = 0;

        for (long j = 0; j < length; j++)
        {
            hr += arr[i][j];
            vr += arr[j][i];
        }

        if (hr != vr || (i > 0 && (hr != bf || vr != bf)))
        {
            isMagic = false;
            break;
        }

        if (i == 0)
            bf = hr;
    }

    if (isMagic)
    {
        for (long i = 0, j = length - 1; i < length; i++, j--)
        {
            ld += arr[i][i];
            rd += arr[j][i];
        }

        if (ld != rd)
            cout << "No" << endl;
        else
            cout << "Yes" << endl;
    }
    else
        cout << "No" << endl;

    return 0;
}