[백준] 11723번 - 집합 [Java]

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

 

[백준] 11723번 - 집합 [Java]

[백준] 11723번 - 집합 [Java]

[백준] 11723번 - 집합 [Java]

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1.  아이디어

 

집합을 구현하는 문제로 Set 자료구조를 활용한 구현과 비트마스킹을 활용한 구현 두가지 방식을 활용했다.

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2. 문제풀이

 

switch 문으로 연산 종류에 맞게 연산을 수행하도록 구현했다.

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3. 코드

 

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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringBuilder sb = new StringBuilder();
        StringTokenizer st;

        int M = Integer.parseInt(br.readLine());

        Set<Integer> set = new HashSet<>();

        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(br.readLine());

            String order = st.nextToken();

            switch (order) {
                case "add":
                    int X = Integer.parseInt(st.nextToken());
                    set.add(X);
                    break;

                case "remove":
                    X = Integer.parseInt(st.nextToken());
                    set.remove(X);
                    break;

                case "check":
                    X = Integer.parseInt(st.nextToken());
                    sb.append(set.contains(X) ? 1 : 0).append("\n");
                    break;

                case "toggle":
                    X = Integer.parseInt(st.nextToken());
                    if (set.contains(X)) set.remove(X);
                    else set.add(X);
                    break;

                case "all":
                    for (int n = 1; n <= 20; n++) {
                        set.add(n);
                    }
                    break;

                case "empty":
                    set.clear();
                    break;
            }
        }

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

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

public class Main_Bitmask {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringBuilder sb = new StringBuilder();
        StringTokenizer st;

        int M = Integer.parseInt(br.readLine());

        int set = 0;

        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(br.readLine());

            String order = st.nextToken();

            switch (order) {
                case "add":
                    int X = Integer.parseInt(st.nextToken());
                    set |= (1 << X);
                    break;

                case "remove":
                    X = Integer.parseInt(st.nextToken());
                    set &= ~(1 << X);
                    break;

                case "check":
                    X = Integer.parseInt(st.nextToken());
                    sb.append(((set & (1 << X)) > 0) ? 1 : 0).append("\n");
                    break;

                case "toggle":
                    X = Integer.parseInt(st.nextToken());
                    if ((set & (1 << X)) > 0) set &= ~(1 << X);
                    else set |= (1 << X);
                    break;

                case "all":
                    for (int n = 1; n <= 20; n++) {
                        set |= (1 << n);
                    }
                    break;

                case "empty":
                    set = 0;
                    break;
            }
        }

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

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4. 후기

 

- Set

- 비트마스킹