找子串替换(kmp)poj1572

#include <string>
#include <iostream>
#include <algorithm>
#include <stdio.h>

using namespace std;

const int maxn = 105;
int n;
string origin[maxn],rep[maxn],sequence;

void init()
{
for(int i=0;i<n;i++)
{
getline(cin,origin[i]);
getline(cin,rep[i]);
}
getline(cin,sequence);
}

void work()
{
int pos;
int len;
for(int i=0;i<n;i++)
{
pos=sequence.find(origin[i]);
len=origin[i].length();
while(pos!=string::npos)
{
sequence.erase(pos,len);
sequence.insert(pos,rep[i]);
pos=sequence.find(origin[i]);
}
}
cout<<sequence<<endl;
}

int main()
{
cin>>n;
getchar();
while(n!=0)
{
init();
work();
cin>>n;
getchar();
}
return 0;
}