Java - 백준 코딩테스트 3052번 [1차원 배열 - 나머지]

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashSet;
 
public class Remainder {
 
    public static void main(String[] args) throws IOException {
        // 20210622 - 3052번 
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        
        int arr[] = new int[10];
        
        for (int i = 0; i < 10; i++) {
            int num = Integer.parseInt(br.readLine());
            arr[i] = num % 42;
        }
 
        int result = 0;
        
        for (int i = 0; i < arr.length; i++) {
            int count = 0;
            
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[i] == arr[j]) {
                    count++;
                }
            }
            if (count == 0) {
                result++;
            }
        }
        
        bw.write(String.valueOf(result));
        bw.flush();
        bw.close();
        br.close();
        
        
        /*
         * HashSet 은 중복된 값을 허용하지 않음.
         * 훨씬 간단하게 풀 수 있음.
         * 
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        HashSet<Integer> hs = new HashSet<Integer>();
        
        for (int i = 0; i < 10; i++) {
            hs.add(Integer.parseInt(br.readLine()) % 42);
        }
        
        System.out.println(hs.size());
        */
    }
}