[백준] 20568 Recess Rocks - Greedy / Java

• 문제 링크

https://www.acmicpc.net/problem/20568

 

• 풀이 코드

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Set;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        Set<Integer> set = new HashSet<>();
        int n = read(), cnt = 0;
        while (n-- > 0) if (!set.add(read())) cnt++;

        bw.write(String.valueOf(cnt));
        bw.flush();
    }

    private static int read() throws IOException {
        int c, n = System.in.read() & 15;
        while ((c = System.in.read()) > 32) n = (n << 3) + (n << 1) + (c & 15);

        return n;
    }

}