N과 M （12）.java

import java.util.*;
import java.io.*;

public class Main {

    static int N;
    static int M;
    static int[] num;
    static int[] arr = new int[9];

    static StringBuilder sb = new StringBuilder();
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());

        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());

        num = new int[N];
        st = new StringTokenizer(br.readLine());
        for(int i = 0; i < N; i++){
            num[i] = Integer.parseInt(st.nextToken());
        }

        Arrays.sort(num);
        bt(0,0);
        System.out.print(sb);
    }

    static void bt(int k, int start){
        if(k == M){
            for(int i = 0; i < M; i++){
                sb.append(arr[i]+" ");
            }
            sb.append("\n");
            return;
        }
        int before = 0;
        for(int i = start; i < N; i++){
            if(before != num[i]){
                arr[k] = num[i];
                before = num[i];
                bt(k+1, i);
            }
        }
    }
}