/*
 * File: comb.kt
 * Purpose: Prints all k-subsets of the first n nonnegative integers
 * Compilation: kotlinc comb.kt
 * Execution: kotlin CombKt n k
 *   where n, k are positive integers (0 <= k <= n)
 * Author: San Skulrattanakulchai
 */

fun main(args: Array<String>) {
    val n = args[0].toInt()
    val k = args[1].toInt()
    val b = BooleanArray(n)

    fun comb(start: Int, i: Int) {
        if (i == k+1) {
            for (j in b.indices)
                if (b[j]) print(" $j")
            println()
        } else for (j in start until (n-k+i)) {
            b[j] = true
            comb(j+1, i+1)
            b[j] = false
        }
    }

    comb(0, 1)
}