2159. Ancient Cipher

Description

Ancient Roman empire had a strong government system with various departments, including a secret service department. Important documents were sent between provinces and the capital in encrypted form to prevent eavesdropping. The most popular ciphers in those times were so called substitution cipher and permutation cipher.
Substitution cipher changes all occurrences of each letter to some other letter. Substitutes for all letters must be different. For some letters substitute letter may coincide with the original letter. For example, applying substitution cipher that changes all letters from ‘A’ to ‘Y’ to the next ones in the alphabet, and changes ‘Z’ to ‘A’, to the message “VICTORIOUS” one gets the message “WJDUPSJPVT”.
Permutation cipher applies some permutation to the letters of the message. For example, applying the permutation <2, 1, 5, 4, 3, 7, 6, 10, 9, 8> to the message “VICTORIOUS” one gets the message “IVOTCIRSUO”.
It was quickly noticed that being applied separately, both substitution cipher and permutation cipher were rather weak. But when being combined, they were strong enough for those times. Thus, the most important messages were first encrypted using substitution cipher, and then the result was encrypted using permutation cipher. Encrypting the message “VICTORIOUS” with the combination of the ciphers described above one gets the message “JWPUDJSTVP”.
Archeologists have recently found the message engraved on a stone plate. At the first glance it seemed completely meaningless, so it was suggested that the message was encrypted with some substitution and permutation ciphers. They have conjectured the possible text of the original message that was encrypted, and now they want to check their conjecture. They need a computer program to do it, so you have to write one.
Input

Input contains two lines. The first line contains the message engraved on the plate. Before encrypting, all spaces and punctuation marks were removed, so the encrypted message contains only capital letters of the English alphabet. The second line contains the original message that is conjectured to be encrypted in the message on the first line. It also contains only capital letters of the English alphabet.
The lengths of both lines of the input are equal and do not exceed 100.
Output

Output “YES” if the message on the first line of the input file could be the result of encrypting the message on the second line, or “NO” in the other case.
Sample Input

JWPUDJSTVP
VICTORIOUS
Sample Output

YES

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思路

这道题误导性较强：一般我们会从original message出发，先进行substitution cipher，再permutation cipher。问题的关键在于：对于实际中的密文，我们很难找出permutation cipher的加密序列，所以很难破解。

换一种思路：破解substitution cipher后，密文和所猜测的明文仅仅是调换了顺序而已。所以将密文和所猜测的明文都看做是随机序列，之后对其中的每个字母出现的次数进行统计，然后按照出现次数由低到高排序，分别得到密文和猜测明文的各字母出现次数的有序序列，比较两个序列，若相同，则输出YES。

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代码

#include <iostream>#include <string.h>#include <algorithm>using namespace std;int main(int argc, char** argv){    int pw[26] = {0};    int pr[26] = {0};    int i = 0;    char str1[101] = {'0'};    char str2[101] = {'0'};    cin >> str1 >> str2;    for(i = 0;i < strlen(str1);i++)    {        pw[str1[i] - 'A']++;    }    for(i = 0;i < strlen(str2);i++)    {        pr[str2[i] - 'A']++;    }    sort(pw,pw + 26); //标准库自带sort(ip_start,ip_end)函数对某连续地址段的对象进行升序快排    sort(pr,pr + 26);    for(i = 0;i < 26;i++)    {            if(pw[i] != pr[i])            {                cout<<"NO"<<endl;                return 0;            }    }    cout<<"YES"<<endl;      return 0;}