[BOJ] 1822 차집합 (JAVA)

https://www.acmicpc.net/problem/1822

1822번: 차집합

Hash Set과 Priority Queue를 이용하여 풀었습니다.

 

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Iterator;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

public class Main {
	
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        StringTokenizer st = new StringTokenizer(br.readLine(), " ");
        int nA = Integer.parseInt(st.nextToken());
        int nB = Integer.parseInt(st.nextToken());
        HashSet<Integer> set = new HashSet<>();
        st = new StringTokenizer(br.readLine(), " ");
        for (int i = 0; i < nA; i++) {
            set.add(Integer.parseInt(st.nextToken()));
        }
        st = new StringTokenizer(br.readLine(), " ");
        for (int i = 0; i < nB; i++) {
            set.remove(Integer.parseInt(st.nextToken()));
        } // end of input

        Iterator<Integer> it = set.iterator();
        PriorityQueue<Integer> pq = new PriorityQueue<>();
        while(it.hasNext()) {
            pq.offer(it.next());
        }

        sb.append(set.size()).append("\n");
        while(!pq.isEmpty()) {
            sb.append(pq.poll()).append(" ");
        }

        System.out.print(sb.toString());

    }
	
}