那几个测试数据都一样，但是都是显示WA

#include<iostream>
using namespace std;
int main()
{
    int n,c=0,a,b=0,d,e,f=0;
    cin >> n;
    for (int i = 1; b<=n*n ; i++)
    {
        cin >> a;
        c++;
        d = c % 2;

        for (int j = 1; j <= a; j++)
        {
            f++;
            e = f % n;
            if (d == 1) cout << 0;
            else cout << 1;
            if (e == 0) cout << endl;
        }
        b = a + b;
    }
    return 0;
}