N과 M(2)

import java.util.Scanner;

public class BOJ_15650 {

    static boolean[] check = new boolean[9];
    static int[] arr = new int[9];

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        go(0, 1, n, m);
    }

    private static void go(int index, int start, int n, int m) {
        if (index == m) {
            for (int i = 0; i < index; i++) {
                System.out.print(arr[i]);
                if (i < m)
                    System.out.print(" ");
            }
            System.out.println();
            return;
        }

        for (int i = start; i <= n; i++) {
            if (check[i])
                continue;
            check[i] = true;
            arr[index] = i;
            go(index + 1, i + 1, n, m);
            check[i] = false;
        }
    }
}