[Java] BOJ 1394 암호

1394번: 암호

---

테스트 코드

abcde
dcb

4 * 5^2 + 3 * 5^1 + 2 * 5^0
= 117

---

정답 코드

• map에 문자 첫번째 위치 저장
• arr에는 N제곱 modular 값 저장

import java.io.*;
import java.util.*;

public class Main {

    static BufferedReader br;
    static BufferedWriter bw;
    static StringTokenizer st;
    static String str1, str2;
    static long[] arr;
    static HashMap<Character, Integer> map;
    static final int MOD_NUMBER = 900_528;

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

        str1 = br.readLine();
        map = new HashMap<>();
        for (int i = 0; i < str1.length(); i++) {
            char c = str1.charAt(i);
            if (!map.containsKey(c)) {
                map.put(c, i + 1);
            }
        }

        long tmp = 1;
        arr = new long[1_000_001];
        arr[0] = tmp;
        for (int i = 1; i < 1_000_001; i++) {
            tmp *= (str1.length() % MOD_NUMBER);
            tmp %= MOD_NUMBER;
            arr[i] = tmp;
        }

        long ans = 0;
        str2 = br.readLine();
        for (int i = 0; i < str2.length(); i++) {
            char c = str2.charAt(i);
            int index = str2.length() - i - 1;
            ans += (map.get(c) * arr[index]) % MOD_NUMBER;
            ans %= MOD_NUMBER;
        }

        System.out.println(ans);
    }
}