Am I making it too complicated ? can anyone tell me what's wrong with the logic ? 9 !! works ok
.............

#include "stdafx.h"
#include <iostream>
#include <string>

using namespace std;
int main()
{
    int n;
    string marks;
    int output = 1;
    cin >> n >> marks;
    int k= marks.length();
    int until = n / k;

    if (n % k != 0) {
        for (int i = 0; i <= until; i++) {
             output *=  (n - i * k);
      }
        output *= (n % k);
    }

    else if (n % k == 0) {
        for (int i = 0; i < k; i++) {
            output *= (n - i * k);
        }
        output *= k;
    }
    cout << output << endl;
    return 0;
}

Edited by author 06.08.2016 07:38