8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 in = new Scanner(System.in);
        String key = in.nextLine();
        String plaintext = in.nextLine();
        Set<Character> chset = new LinkedHashSet<>();
        // 去重并且保证顺序
        char [] keyArr = key.toCharArray();
        for(int i = 0;i<keyArr.length;i++){
            chset.add(Character.toLowerCase(keyArr[i]));
        }
        Iterator it = chset.iterator();
        LinkedHashSet<Character>  lset = new LinkedHashSet<>();
        lset.addAll(Arrays.asList('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'));

        // 先缓存单词字母，然后移除变化的字母
        List<Character> charList = new ArrayList<>();

        char[] upperKeychar = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
        char[] lowerKeychar = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
        while(it.hasNext()){
            Character aaa = (Character)it.next();
            charList.add(aaa);
            lset.remove(aaa);
        }
        
        // System.out.println(charList.toString());
        // System.out.println(lset);
        charList.addAll(lset);
        // System.out.println(Arrays.toString(upperKeychar));
        // System.out.println(charList.toString());



        Map<Character,Character> resultLowermap = new LinkedHashMap<>();
        Map<Character,Character> resultUppermap = new LinkedHashMap<>();
        // 存放加密映射
        for(int i = 0;i<26;i++){
            resultLowermap.put(lowerKeychar[i],charList.get(i));
            resultUppermap.put(upperKeychar[i],Character.toUpperCase(charList.get(i)));
        }

        // 对数据进行加密处理
        StringBuilder sb = new StringBuilder();
        for(int i = 0;i<plaintext.length();i++){
            char ch = plaintext.charAt(i);
            if(Character.isLowerCase(ch)){
                sb.append(resultLowermap.get(ch));
            }else if(Character.isUpperCase(ch)){
                sb.append(resultUppermap.get(ch));
            }else{
                sb.append(plaintext.charAt(i));
            }
        }
        System.out.println(sb.toString());
    }
}