hdu 4300 Clairewd’s message

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Clairewd是一名FBI成员，在北京邮电大学潜伏多年，截获了一些重要信息并准备发送给ykwd。两人约定使用转换表将每条消息中的字母替换为另一个字母。不幸的是，GFW发现了他们的行动，并在未知情况下获得了转换表。

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Clairewd’s message

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 7739 Accepted Submission(s): 2867

Problem Description

Clairewd is a member of FBI. After several years concealing in BUPT, she intercepted some important messages and she was preparing for sending it to ykwd. They had agreed that each letter of these messages would be transfered to another one according to a conversion table.
Unfortunately, GFW(someone's name, not what you just think about) has detected their action. He also got their conversion table by some unknown methods before. Clairewd was so clever and vigilant that when she realized that somebody was monitoring their action, she just stopped transmitting messages.
But GFW knows that Clairewd would always firstly send the ciphertext and then plaintext(Note that they won't overlap each other). But he doesn't know how to separate the text because he has no idea about the whole message. However, he thinks that recovering the shortest possible text is not a hard task for you.
Now GFW will give you the intercepted text and the conversion table. You should help him work out this problem.

Input

The first line contains only one integer T, which is the number of test cases.
Each test case contains two lines. The first line of each test case is the conversion table S. S[i] is the ith latin letter's cryptographic letter. The second line is the intercepted text which has n letters that you should recover. It is possible that the text is complete.

Hint

Range of test data:
T<= 100 ;
n<= 100000;

Output

For each test case, output one line contains the shorest possible complete text.

Sample Input

      
       2
abcdefghijklmnopqrstuvwxyz
abcdab
qwertyuiopasdfghjklzxcvbnm
qwertabcde

Sample Output

      
       abcdabcd
qwertabcde

拓展kmp，看了别人的作为参考，第一次做这个，想不出来。

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
const int N=2e5+10;
char s[N],a[N],pass[N];
int Next[N];
void getNext(char str[],int len)
{
    Next[0]=-1;
    int i=0,j=-1;
    while(i<len)
    {
        if(j==-1||str[i]==str[j])
        {
            i++;
            j++;
            Next[i]=j;
        }
        else
            j=Next[j];
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int i;
        scanf("%s%s",s,a);
        for(i=0;s[i];i++)
            pass[s[i]-'a']=i+'a';
        int len=strlen(a);
        int mid=(len+1)/2;
        for(i=0;i<mid;i++)
            s[i]=pass[a[i]-'a'];
        s[i]='*';
        s[i+1]=0;
        strcat(s,a+i);
        getNext(s,len+1);
        mid=len-Next[len+1];
        for(i=0;i<mid;i++)
        {
            s[i]=a[i];
            s[i+mid]=pass[a[i]-'a'];
        }
        s[i+mid]=0;
        printf("%s\n",s);
    }
    return 0;
}

参考网址：

https://www.cnblogs.com/liuxin13/p/4732661.html