[sicily online]1036. Crypto Columns

本文详细介绍了列式加密的原理与实现过程,通过关键词与输入输出示例,展示了如何使用特定算法从密文中恢复原始明文信息。文章深入探讨了加密解密过程中涉及的数据排列、字母顺序调整等关键步骤,旨在为信息安全领域的开发者提供实用的技术解决方案。

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/*
Constraints
Time Limit: 1 secs, Memory Limit: 32 MB 

Description
The columnar encryption scheme scrambles the letters in a message (or plaintext) using a keyword as illustrated in the following example: Suppose BATBOY is the keyword and our message is MEET ME BY THE OLD OAK TREE. Since the keyword has 6 letters, we write the message (ignoring spacing and punctuation) in a grid with 6 columns, padding with random extra letters as needed: 

MEETME
BYTHEO
LDOAKT
REENTH

Here, we've padded the message with NTH. Now the message is printed out by columns, but the columns are printed in the order determined by the letters in the keyword. Since A is the letter of the keyword that comes first in the alphabet, column 2 is printed first. The next letter, B, occurs twice. In the case of a tie like this we print the columns leftmost first, so we print column 1, then column 4. This continues, printing the remaining columns in order 5, 3 and finally 6. So, the order the columns of the grid are printed would be 2, 1, 4, 5, 3, 6, in this case. This output is called the ciphertext, which in this example would be EYDEMBLRTHANMEKTETOEEOTH. Your job will be to recover the plaintext when given the keyword and the ciphertext.


Input

There will be multiple input sets. Each set will be 2 input lines. The first input line will hold the keyword, which will be no longer than 10 characters and will consist of all uppercase letters. The second line will be the ciphertext, which will be no longer than 100 characters and will consist of all uppercase letters. The keyword THEEND indicates end of input, in which case there will be no ciphertext to follow.


Output
For each input set, output one line that contains the plaintext (with any characters that were added for padding). This line should contain no spacing and should be all uppercase letters.

Sample Input
BATBOY
EYDEMBLRTHANMEKTETOEEOTH
HUMDING
EIAAHEBXOIFWEHRXONNAALRSUMNREDEXCTLFTVEXPEDARTAXNAARYIEX
THEENDSample Output
MEETMEBYTHEOLDOAKTREENTH
ONCEUPONATIMEINALANDFARFARAWAYTHERELIVEDTHREEBEARSXXXXXX
*/
#include<iostream>
#include<cmath>
#include<iomanip>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

int main()
{
	string keyword,ciphertext;
	while(cin>>keyword&&keyword!="THEEND")
	{
		vector< pair<char,int> > key;
		for(string::size_type i=0;i<keyword.size();i++)
		{
			key.push_back(make_pair(keyword[i],i));
		}

		sort(key.begin(),key.end());
		cin>>ciphertext;
		string text(ciphertext.size(),'0');
		for(string::size_type i=0;i<key.size();i++)
		{
			for(string::size_type j=0;j<ciphertext.size()/keyword.size();j++)
				text[key[i].second*ciphertext.size()/keyword.size()+j]=ciphertext[i*ciphertext.size()/keyword.size()+j];
		}
		for(string::size_type i=0;i<ciphertext.size()/keyword.size();i++)
		{
			for(string::size_type j=0;j<key.size();j++)
				cout<<text[j*ciphertext.size()/keyword.size()+i];
		}
		cout<<endl;
	}//end while
}

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