编辑代码

import java.util.*;

public class Main{
    static int n;
    static int m;
    static int ans;
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        n = scan.nextInt();
        m = scan.nextInt();
        int[] dp = new int[n];
        f(1,0,dp);
        System.out.println(ans);
    }
    public static void f(int k,int cnt,int[]dp)
    {
        if(cnt>m||k>n+1)
        {
            return;
        }
        if(k==n+1&&cnt==m)
        {
            ans++;
            String s = "";
            for(int i = 0;i<m;i++)
            {
                s = s+" "+dp[i];
            }
            System.out.println(s);
            return;
        }
        for(int i = 1;i>=0;i--)
        {
            if(i==0)
            { 
                f(k+1,cnt,dp);
            }
            else
            {
                dp[cnt] = k;
                f(k+1,cnt+1,dp);
            }
        }
    }
}