Java

import java.util.Scanner;
public class Main {
    static int []way = new int[30];
    static int n,m;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();
        dfs(1,1);
    }
    public static void dfs(int num,int start){
        if(num>m){
            for(int i=1; i<=m; i++){
                System.out.print(way[i] + " ");
            }
            System.out.println();
            return;
        }
        for(int i=start; i<=n; i++){
            way[num]=i;
            dfs(num+1, i+1);
            way[num]=0;
        }
    }
}