/*
 * File: perm.c
 * Purpose: Prints all permutations of [n]
 * Compilation: gcc -o perm perm.c
 * Execution: ./perm n
 *   where n is a positive integer
 * Author: San Skulrattanakulchai
 */

#include <stdio.h>
#include <stdlib.h>

void swap(int a[], int i, int k) {
    int temp = a[i];
    a[i] = a[k];
    a[k] = temp;
}

void printArray(int a[], int size) {
    int i;
    printf("%d", a[0]);
    for (i = 1; i < size; i++)
        printf(", %d", a[i]);
    putchar('\n');
}

void perm(int k, int pi[], int size) {
    if (k == size)
        printArray(pi, size);
    else {
        int i;
        for (i = k; i < size; i++) {
            swap(pi, i, k);
            perm(k+1, pi, size);
            swap(pi, i, k);
        }
    }
}

int main(int argc, char **argv) {
    int n = atoi(argv[1]);
    int *pi = malloc(n * sizeof(int));
    int i;
    for (i = 0; i < n; i++)
        pi[i] = i;
    perm(0, pi, n);
    return 0;
}