241214-15655.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

    static int N;
    static int M;
    static int[] arr;
    static int[] result;
    static StringBuilder sb;

    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());
        arr = new int[N];
        result = new int[M];
        st = new StringTokenizer(br.readLine());
        for (int i = 0; i < N; i++) {
            arr[i] = Integer.parseInt(st.nextToken());
        }
        Arrays.sort(arr);
        sb = new StringBuilder();
        solve(0, 0);
        System.out.print(sb);
    }

    static void solve(int idx, int depth) {
        if (depth == M) {
            for (int i = 0; i < M; i++) {
                sb.append(result[i]).append(" ");
            }
            sb.append("\n");
            return;
        }
        for (int i = idx; i < N; i++) {
            result[depth] = arr[i];
            solve(i + 1, depth + 1);
        }
    }
}