permutation.cpp

#include <iostream>

using namespace std;

int fact(int k)
{
    if( k == 0 ) return 1;
    return k * fact(k-1);
}

int permutations(int n, int r)
{
    return (fact(n) / fact(n-r));
}

int main()
{
    int n = 4;
    int r = 3;

    int p = permutations(n, r);

    cout << "permutations(" << n << "," << r << ") = " << p << endl;
    
    return 0;
}