boj_15649.java

package backtracking;

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

public class boj_15649 {
    static int N;
    static int M;
    static int[] arr;
    static boolean[] check;

    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[M+1];
        check = new boolean[N+1];

        dfs(0);

    }

    public static void dfs(int depth) {
        if (depth == M) {
            for (int i = 0; i < M; i++) {
                System.out.print(arr[i] + " ");
            }
            System.out.println();
            return;
        }

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

    }
}