N과 M(4)

import java.util.Scanner;

public class BOJ_15652 {

    static int[] arr = new int[8];

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int m = sc.nextInt();

        go(0, n, m);
    }

    private static void go(int index, int n, int m) {

        if (index == m) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < m; i++) {
                sb.append(arr[i]);
                sb.append(" ");
            }
            sb.append("\n");
            System.out.print(sb.toString());
            return;
        }

        for (int i = 1; i <= n; i++) {
            if(index > 0){
                if(arr[index-1] > i)
                    continue;
            }
            arr[index] = i;
            go(index + 1, n, m);
        }
    }
}