Uva 12024 Solution

#include<bits/stdc++.h>
#define ll long long int
using namespace std;

ll permutation[13] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600};

ll Derangement_Number(int n)
{
    int d[n+1], i;

    d[0] = 1;
    d[1] = 0;
    d[2] = 1;

    for(i=3;i<=n;i++)
        d[i] = (i-1) * (d[i-1] + d[i-2]);

    return d[n];
}

int main()
{
    int t, n;
    cin >> t;
    while(t--)
    {
        cin >> n;

        ll r = Derangement_Number(n);

        cout << r << "/" << permutation[n] << "\n";
    }

    return 0;
}