BOJ - 집합

https://www.acmicpc.net/problem/11723

11723번: 집합

 

• 비트마스킹을 활용한 문제이다.
• 문제의 입력 수가 3,000,000 이기에 System.out.println 함수를 사용 할 경우 시간 초과가 날 수 있다.
  • StringBuilder 를 활용하면 된다!

 

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


public class Main {
    public static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    private static int bit = 0;
    private static StringBuilder builder = new StringBuilder();

    public static void main(String[] args) throws Exception {
        int M = Integer.parseInt(br.readLine());

        StringTokenizer st;
        while (M-- > 0) {
            st = new StringTokenizer(br.readLine());

            String command = st.nextToken();

            switch(command) {
                case "add":
                    add(Integer.parseInt(st.nextToken()));
                    break;
                case "remove":
                    remove(Integer.parseInt(st.nextToken()));
                    break;
                case "check":
                    check(Integer.parseInt(st.nextToken()));
                    break;
                case "toggle":
                    toggle(Integer.parseInt(st.nextToken()));
                    break;
                case "all":
                    bit = 0x1FFFFE;
                    break;
                case "empty":
                    bit = 0;
                    break;
            }
        }

        System.out.println(builder);
    }

    public static void add(int position) {
        bit |= (0x1 << position);
    }

    public static void remove(int position) {
        bit &= ~(0x1 << position);
    }

    public static void check(int position) {
        builder.append(((bit & (0x1 << position)) >> position) + "\n");
    }

    public static void toggle(int position) {
        bit ^= (0x1 << position);
    }
}