这道题弹了非常久的TLE，发现不能一个字符一个字符地输出。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
using namespace std;
const int maxn = 100000+10;
const int esize = 28;
int next[maxn],mid;
char mp[esize],str[maxn];
string str1,str2;

void getNext(){
    next[0] = next[1] = 0;
    int n = str1.size();
    for(int i = 1,j; i < n; i++){
        j = next[i];
        while(j && str1[i] != str1[j]) j = next[j];
        if(str1[i] == str1[j]) next[i+1] = j+1;
        else next[i+1] = 0;
    }
}

void KMP(int sta){
    int n = strlen(str) , j = 0;
    for(int i = sta; i < n; i++){
        while(j && str1[j] != str[i]) j = next[j];
        if(str1[j] == str[i]) j++;
        if(j==str1.size()) break;
    }
    int  k;
    if(n%2==0) k = sta-j;
    else k = sta-j-1;
    for(int i = 0; i < k; i++){
        str1 += mp[str[sta+i]-‘a‘];
        str2 += str[sta+i];
    }
    cout<<str2<<str1<<endl;

}
int main(){
    int ncase;
    cin >> ncase;
    char tmp[esize];
    getchar();
    while(ncase--){
        scanf("%s%s",tmp,str);
        int n = strlen(str);
        if(n==0){
            puts("");
            continue;
        }
        str1.clear();
        str2.clear();
        for(int i = 0; i < 26; i++)
            mp[tmp[i]-‘a‘] = char(‘a‘+i);
        if(n%2==0) mid = n/2-1;
        else mid = n/2;
        for(int i = 0; i <= mid; i++){
            str1 += mp[str[i]-‘a‘];
            str2 += str[i];
        }
        getNext();
        KMP(mid+1);
    }
    return 0;
}