/*
 * File: perm.kt
 * Purpose: Prints all permutations of the first n nonnegative integers
 * Compilation: kotlinc perm.kt
 * Execution: kotlin PermKt n
 *   where n is a positive integer
 * Author: San Skulrattanakulchai
 */

fun main(args: Array<String>) {
    val n = args[0].toInt()
    val a = IntArray(n) { it }

    fun swap(i: Int, k: Int) {
        val temp = a[i]
        a[i] = a[k]
        a[k] = temp
    }

    fun perm(k: Int) {
        if (k == n)
            println(a.joinToString())
        else for (i in k until n) {
            swap(i, k)
            perm(k+1)
            swap(i, k)
        }
    }

    perm(0)
}