题解 | #字符串加密#

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String key = sc.next();
        String password = sc.next();
        Set<Character> set = new LinkedHashSet<>();
        for (int i = 0; i < key.length(); i++) {
            set.add(key.charAt(i));
        }
        Map<Character, Character> dic = new HashMap<>();
        // 记录密钥
        int i = 0;
        for (Character ch : set) {
            char plain = (char) ('a' + i);
            dic.put(plain, ch);
            i++;
        }

        // 记录剩余的字母
        Set<Character> set1 = new LinkedHashSet<>();
        for (int j = 0; j < 26; j++) {
            char ch = (char) ('a' + j);
            if (!set.contains(ch)) {
                set1.add(ch);
            }
        }

        // 密文配对
        for (Character ch : set1) {
            char plain = (char) ('a' + i);
            dic.put(plain, ch);
            i++;
        }

        StringBuilder ans = new StringBuilder();
        for (int j = 0; j < password.length(); j++) {
            ans.append(dic.get(password.charAt(j)));
        }
        System.out.println(ans);
    }
}