题解 | #字符串加解密#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String line1 = reader.readLine();
        String line2 = reader.readLine();

        StringBuilder sb1 = new StringBuilder();
        for (int i = 0; i < line1.length(); ++i) {
            char ascii = line1.charAt(i);
            sb1.append(encode(ascii));
        }

        StringBuilder sb2 = new StringBuilder();
        for (int i = 0; i < line2.length(); ++i) {
            char ascii = line2.charAt(i);
            sb2.append(decode(ascii));
        }

        System.out.println(sb1);
        System.out.println(sb2);
    }

    /**
     * 
     * 加密过程
     * 小写字母：a-z +1 -97 %26 +97 后取大写
     * 大写字母：A-Z +1 -65 %26 +65 后取小写
     * 数字内容：0-9 +1 -48 %10 +48
     * 
     * @param ascii
     * @return
     */
    public static char encode(char ascii) {
        if (ascii >= 'a' && ascii <= 'z') {
            ascii = (char) ((ascii + 1 - 'a') % ('z'-'a' + 1) + 'a');
            ascii = Character.toUpperCase(ascii);
            return ascii;
        }

        if (ascii >= 'A' && ascii <= 'Z') {
            ascii = (char) ((ascii + 1 - 'A') % ('Z'-'A' + 1) + 'A');
            ascii = Character.toLowerCase(ascii);
            return ascii;
        }

        if (ascii >= '0' && ascii <= '9') {
            ascii = (char) ((ascii + 1 - '0') % ('9'-'0' + 1) + '0');
            return ascii;
        }

        return ascii;
    }

    /**
     * 
     * 解密过程
     * 小写字母：转成大写 -65 (-1 + 26) % 26 + 65
     * 大写字母：转成小写 -97 (-1 + 26) % 26 + 97
     * 数字内容：-48 (-1 + 10) % 10 + 48
     * 
     * @param ascii
     * @return
     */
    public static char decode(char ascii) {
        if (ascii >= 'a' && ascii <= 'z') {
            ascii = Character.toUpperCase(ascii);
            ascii = (char) ((ascii - 'A' - 1 + ('Z' - 'A' + 1)) % ('Z' - 'A' + 1) + 'A');
            return ascii;
        }

        if (ascii >= 'A' && ascii <= 'Z') {
            ascii = Character.toLowerCase(ascii);
            ascii = (char) ((ascii - 'a' - 1 + ('z' - 'a' + 1)) % ('z' - 'a' + 1) + 'a');
            return ascii;
        }

        if (ascii >= '0' && ascii <= '9') {
            ascii = (char) ((ascii - '0' - 1 + ('9' - '0' + 1)) % ('9' - '0' + 1) + '0');
            return ascii;
        }

        return ascii;
    }
}