递归

java 代码

import java.util.Scanner;
public class Main{
    static int N = 25;
    static int[] path = new int[N];
    static int n,k;
    public static void dfs(int k,int s,int l){
        if(k == 0) {
            for(int i = l - 1 ; i >= 0 ;i --) System.out.print(path[i]+" ");
            System.out.println();
            return;
        }
        for(int i = s; i <= n; i++){
            path[k - 1] = i;
            dfs(k - 1, i + 1, l);
        }
    }
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        n = in.nextInt();
        k = in.nextInt();
        dfs(k,1,k);
    }
}