백준 10986번

원본 : https://www.acmicpc.net/problem/10986

10986번: 나머지 합

 

풀이

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    private static final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    private static final StringBuilder stringBuilder = new StringBuilder();

    public static void main(String[] args) throws Exception {
        StringTokenizer stringTokenizer = new StringTokenizer(bufferedReader.readLine());
        int n = Integer.parseInt(stringTokenizer.nextToken());
        int m = Integer.parseInt(stringTokenizer.nextToken());
        long[] remainder = new long[m];

        stringTokenizer = new StringTokenizer(bufferedReader.readLine());

        int sum = 0;
        while (stringTokenizer.hasMoreTokens()) {
            sum = (sum + Integer.parseInt(stringTokenizer.nextToken())) % m;
            remainder[sum]++;
        }

        long count = remainder[0];

        for (int i = 0; i < m; i++) {
            count += (remainder[i] * (remainder[i] - 1)) / 2;
        }

        System.out.println(stringBuilder.append(count));
    }
}