[백준] N과M(9)

Set을 이용하여 중복 제거

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

public class Main {
    private static StringBuilder sb = new StringBuilder();
    private static int[] element;
    private static int[] arr;
    private static boolean[] visit;
    private static Set<String> set = new HashSet<>();


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

        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);
        System.out.println(sb);
    }

    private static void bt(int n, int m, int depth) {
        if (depth == m) {
            StringBuilder sb2 = new StringBuilder();
            for (int i : arr) {
                sb2.append(i + " ");
            }
            sb2.append("\n");

            if (!set.contains(sb2.toString())) {
                sb.append(sb2);
                set.add(sb2.toString());
            }
            return;
        }

        for (int i = 0; i < element.length; i++) {
            if (!visit[i]) {
                visit[i] = true;
                arr[depth] = element[i];
                bt(n, m, depth + 1);
                visit[i] = false;
            }
        }
    }
}