自己写的。

import java.util.Scanner;
import java.lang.*;


public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            String key = in.nextLine();
            String key_back = key;
            String str = in.nextLine();
            char[] table = new char[26];
            int k = 0;
            for (int i = 0; i < key.length();) {
                String temp = key.substring(i, i + 1);
                String temp2 = key.substring(i + 1);
                if (temp2 == null || !temp2.contains(temp)) {
                    table[k++] = temp.charAt(0);
                    key = temp2;
                } else {
                    StringBuffer sb = new StringBuffer(temp2);
                    while (sb.indexOf(temp) != -1) {
                        sb.deleteCharAt(sb.indexOf(temp));
                    }
                    key = sb.toString();
                    table[k++] = temp.charAt(0);
                }
            }
            String old = "abcdefghijklmnopqrstuvwxyz";
            for (int i = 0; i < k; i++) {
                StringBuffer sb2 = new StringBuffer(old);
                sb2.deleteCharAt(sb2.indexOf(Character.toString(table[i])));
                old = sb2.toString();
            }
            for (int i = 0; k < 26; k++) {
                table[k] = old.charAt(i++);
            }
            String res = "";
            for (int i = 0; i < str.length(); i++) {
                res += Character.toString((table[str.charAt(i) - 'a']));
            }
            System.out.println(res);
        }
    }
}