[백준] N과M(6)

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

public class Main {
	private static StringBuilder sb = new StringBuilder();
	private static int[] element;
	private static boolean[] visit;
	private static int[] arr;

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();
		StringTokenizer st = new StringTokenizer(line);
		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());

		element = new int[n];
		visit = new boolean[n];
		arr = new int[m];

		line = br.readLine();
		st = new StringTokenizer(line);

		for (int i = 0; i < element.length; i++) {
			element[i] = Integer.parseInt(st.nextToken());
		}

		Arrays.sort(element);

		bt(n, m, 0, 0);
		System.out.println(sb);
	}

	private static void bt(int n, int m, int depth, int start) {
		if (depth == m) {
			for (int i : arr) {
				sb.append(i + " ");
			}
			sb.append("\n");
			return;
		}

		for (int i = start; i < element.length; i++) {
			if (!visit[i]) {
				visit[i] = true;
				arr[depth] = element[i];
				bt(n, m, depth + 1, i + 1);
				visit[i] = false;
			}
		}
	}

}