UVa 133 - The Dole Queue

#include <iostream>
#include <iomanip>
#include <string.h>
using namespace std;

bool used[20] = {};
int n, k, m;
int go(int begin, int sum, int step)
{
    while (sum--)
    {
        do
        {
            begin = (begin + step + n - 1) % n + 1;
        } while (used[begin]);
    }
    return begin;
}

int main()
{
    while (cin >> n >> k >> m && n)
    {
        memset(used, false, sizeof(used));
        int left = n;
        int a1 = n, a2 = 1;
        while (left > 0)
        {
            a1 = go(a1, k, 1);
            left--;
            cout << setw(3) << a1;
            if (!left)
                break;
            a2 = go(a2, m, -1);
            used[a1] = used[a2] = true;
            if (a1 != a2)
            {
                cout << setw(3) << a2;
                left--;
            }
            if (left)
                cout << ",";
        }
        cout << endl;
    }
    return 0;
}