백준 15649번, N과 M (1) (with.Java)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.IOException;

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

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        String[] s_arr = br.readLine().split(" ");
        br.close();
        int N = Integer.valueOf(s_arr[0]);
        int M = Integer.valueOf(s_arr[1]);

        arr = new int[M];
        visit = new boolean[N];

        dfs(N, M, 0);

        bw.write(sb.toString());
        bw.flush();
        bw.close();
    }

    public static void dfs(int N, int M, int depth){
        if(depth == M){
            for(int i : arr){
                sb.append(i).append(" ");
            }
            sb.append("\n");
            return;
        }

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