P1079 [NOIP2012 提高组] Vigenère 密码

一起来交流编程吧【CSDN app】：
http://qm.qq.com/cgi-bin/qm/qr?_wv=1027&k=x9pL9ccIHGKNLE0CWviAqQ_q6HzxomLW&authKey=VslKe623ptw8VRepda%2Bh0Ttr8Ruz8v%2FBW5HpVzyTWU7ECwpHIZpULMj6qIHYZBVb&noverify=0&gro

[NOIP2012 提高组] Vigenère 密码

题目描述

16 世纪法国外交家 Blaise de Vigenère 设计了一种多表密码加密算法 Vigenère 密码。Vigenère 密码的加密解密算法简单易用，且破译难度比较高，曾在美国南北战争中为南军所广泛使用。

在密码学中，我们称需要加密的信息为明文，用 $M$ 表示；称加密后的信息为密文，用 $C$ 表示；而密钥是一种参数，是将明文转换为密文或将密文转换为明文的算法中输入的数据，记为 $k$ 。在 Vigenère 密码中，密钥 $k$ 是一个字母串， $k=k_1,k_2,…,k_n$ 。当明文 $M=m_1,m_2,…,m_n$ 时，得到的密文 $C=c_1,c_2,…,c_n$ ，其中 $c_i$ = $m_i \operatorname{\circledR} k_i$ ，运算 $\circledR$ 的规则如下表所示：

$$\begin{array}{c|cccccccccccccccccccccccccc}
\circledR &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} \\hline
\tt A &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} \
\tt B &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} \
\tt C &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} \
\tt D &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} \
\tt E &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} \
\tt F &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} \
\tt G &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} \
\tt H &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} \
\tt I &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} \
\tt J &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} \
\tt K &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} \
\tt L &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} \
\tt M &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} \
\tt N &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} \
\tt O &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} \
\tt P &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} \
\tt Q &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} \
\tt R &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} \
\tt S &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} \
\tt T &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} \
\tt U &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} \
\tt V &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} \
\tt W &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} \
\tt X &\tt X \kern{-5pt} &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} \
\tt Y &\tt Y \kern{-5pt} &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} \
\tt Z &\tt Z \kern{-5pt} &\tt A \kern{-5pt} &\tt B \kern{-5pt} &\tt C \kern{-5pt} &\tt D \kern{-5pt} &\tt E \kern{-5pt} &\tt F \kern{-5pt} &\tt G \kern{-5pt} &\tt H \kern{-5pt} &\tt I \kern{-5pt} &\tt J \kern{-5pt} &\tt K \kern{-5pt} &\tt L \kern{-5pt} &\tt M \kern{-5pt} &\tt N \kern{-5pt} &\tt O \kern{-5pt} &\tt P \kern{-5pt} &\tt Q \kern{-5pt} &\tt R \kern{-5pt} &\tt S \kern{-5pt} &\tt T \kern{-5pt} &\tt U \kern{-5pt} &\tt V \kern{-5pt} &\tt W \kern{-5pt} &\tt X \kern{-5pt} &\tt Y \kern{-5pt} \

\end{array}
$$

Vigenère 加密在操作时需要注意：

$\circledR$ 运算忽略参与运算的字母的大小写，并保持字母在明文 $M$ 中的大小写形式；
当明文 $M$ 的长度大于密钥 $k$ 的长度时，将密钥 $k$ 重复使用。

例如，明文 $M=\texttt{Helloworld}$ ，密钥 $k=\texttt{abc}$ 时，密文 $C=\texttt{Hfnlpyosnd}$ 。

$KaTeX parse error: Expected a control sequence at position 6: \def{̲\arraystretch}{…$

输入格式

共 2 行。

第一行为一个字符串，表示密钥 $k$ ，长度不超过 $100$ ，其中仅包含大小写字母。

第二行为一个字符串，表示经加密后的密文，长度不超过 $1000$ ，其中仅包含大小写字母。

输出格式

一个字符串，表示输入密钥和密文所对应的明文。

样例 #1

样例输入 #1

CompleteVictory
Yvqgpxaimmklongnzfwpvxmniytm

样例输出 #1

Wherethereisawillthereisaway

提示

对于 $100\%$ 的数据，输入的密钥的长度不超过 $100$ ，输入的密文的长度不超过 $1000$ ，且都仅包含英文字母。

NOIP 2012 提高组第一天第一题

#include<bits/stdc++.h>
using namespace std;
long long q,w,r,t,y,u,i,o,p,s,g,h,j,k,l,m,n,v,x,z,kk,d[10000];
string b,a;
int main()
{cin>>b>>a;for(i=1;i<=b.size();i++){if(b[i-1]<='Z'&&b[i-1]>='A')d[i]=b[i-1]-65;if(b[i-1]<='z'&&b[i-1]>='a')d[i]=b[i-1]-97;}for(i=1;i<=a.size();i++){if(a[i-1]<='Z'&&a[i-1]>='A'){a[i-1]-=d[(i-1)%b.size()+1];if(a[i-1]<65)a[i-1]+=26;}if(a[i-1]<='z'&&a[i-1]>='a'){a[i-1]-=d[(i-1)%b.size()+1];if(a[i-1]<97)a[i-1]+=26;} }cout<<a;return 0;
}