题解 | #字符串加解密#

import java.util.Scanner;

public class Main {
    public static String ENCRY = "encry";
    public static String DECRY = "decry";
    
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNextLine()){
            String ec = scanner.nextLine();
            changeStr(ec,ENCRY);
            String dc = scanner.nextLine();
            changeStr(dc,DECRY);
        }
    }

    private static void changeStr(String sc, String encryType) {
        StringBuilder builder = new StringBuilder();
        for (char c : sc.toCharArray()) {
            if (Character.isLetter(c)){
                if (ENCRY.equals(encryType)) {
                    if (c=='Z'){
                        builder.append('a');
                    } else if(c=='z'){
                        builder.append('A');
                    }else if (Character.isLowerCase(c)){
                        builder.append((char)(c-32+1));
                    } else {
                        builder.append((char)(c+32+1));
                    }
                }else {
                    if (c=='A'){
                        builder.append('z');
                    } else if(c=='a'){
                        builder.append('Z');
                    }else if (Character.isLowerCase(c)){
                        builder.append((char)(c-32-1));
                    } else {
                        builder.append((char)(c+32-1));
                    }
                }
            } else if (Character.isDigit(c)){
                if (ENCRY.equals(encryType)) {
                    if (c == '9') {
                        builder.append('0');
                    } else {
                        builder.append((char) ((int) c + 1));
                    }
                }else {
                    if (c == '0') {
                        builder.append('9');
                    } else {
                        builder.append((char) ((int) c - 1));
                    } 
                }
            }
        }
        System.out.println(builder.toString());
    }
}