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;
}