[백준] 15651번 N과 M (3)

https://www.acmicpc.net/problem/15651

15651번: N과 M (3)

 

시간초과에 유의

 

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

public class Main {

    public static int N, M;
    public static int[] arr;
    public static boolean[] visit;
    public static StringBuffer sb = new StringBuffer();

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

        N = Integer.parseInt(st.nextToken()); // 자연수
        M = Integer.parseInt(st.nextToken()); // 길이
        arr = new int[M];
        visit = new boolean[N];
        dfs(0);
        System.out.println(sb);
    }

    private static void dfs(int depth) {

        if (M == depth) {
            for (int num : arr) {
           		sb.append(num).append(" ");
            }
            sb.append("\n");
            return;
        }

        for (int i = 0; i < N; i++) {
            visit[i] = true;
            arr[depth] = i + 1;
            dfs(depth + 1);
            visit[i] = false;
        }

    }
}