题解 | #字符串加密#

import java.util.Scanner;
import java.util.HashMap;
import java.util.HashSet;

// 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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String key = in.nextLine();
            String str = in.nextLine();

            decode(key, str);
        }
    }

    public static void decode(String key, String str) {
        HashSet<Character> set = new HashSet<>();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < key.length(); i++) {
            char ch = key.charAt(i);
            if (!set.contains(ch)) {
                set.add(ch);
                sb.append(ch);
            }
        }

        //去除了重复字母
        String newKey = sb.toString();
        //System.out.println(newKey);

        //存储映射后的字符串
        StringBuilder mapedStr = new StringBuilder();
        mapedStr.append(newKey);
        for (int i = 0; i < 26; i++) {
            char ch = (char) ('a' + i);
            if (!set.contains(ch)) {
                mapedStr.append(ch);
            }
        }
        //System.out.println(mapedStr);

        HashMap<Character, Character> resultMap = new HashMap<>();
        for (int i = 0; i < 26; i++) {
            char ch = (char) ('a' + i);
            resultMap.put(ch, mapedStr.charAt(i));
        }

        StringBuilder result = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            Character newCh = resultMap.get(ch);
            result.append(newCh);
        }
        System.out.println(result.toString());
    }
}

就是无脑模拟加密后字符串的生成规则即可。