15829 Hashing 🟫

https://www.acmicpc.net/problem/15829

문제 자체는 어렵지 않았지만
int형 데이터를 초과하기 때문에 long이나 BigInteger를 사용하는것이 관건이다.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class Main {

  static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
  static StringTokenizer st;
  static long sum = 0;
  static long pow = 1;

  public static void main(String[] args) throws IOException {
    st = new StringTokenizer(br.readLine());
    int num = Integer.parseInt(st.nextToken());
    st = new StringTokenizer(br.readLine());
    String s = st.nextToken();
    for (int i = 0; i < num; i++) {
      sum += (s.charAt(i) - 96) * pow;
      pow = (pow * 31) % 1234567891;
    }

    bw.write(sum % 1234567891 + "\n");
    bw.close();
    br.close();
  }
}