perm.cpp

#include <iostream>
#include <algorithm>
using namespace std;

//////////////////////////////////////////////////////////////////////////////
//                        Permute array of integers                         //
//////////////////////////////////////////////////////////////////////////////


// roll your own factorial function
int factorial(const int& x)
{
    return (x == 1 || x == 0) ? 1 : factorial(x-1) * x;
}


void permute_array(const int& n)
{
    // create an array from 1 to n
    int my_ints[n];
    for (int i=0; i<=n; i++) {
        my_ints[i] = i+1;
    }

    do {
        for (int j=0; j<n; j++) {
            cout << my_ints[j] << " "; // print permutation
        }
    cout << endl;
    // some sort of magic? permute in place
    } while (next_permutation(my_ints, my_ints+n));
}


int main()
{
    // take integer from stdin
    int input;
    cin >> input;
    int n_permutations = factorial(input);

    // print output to stdout
    cout << n_permutations << endl;
    permute_array(input);
    return 0;
}