KMP

#include <iostream>
using namespace std;

int KMPIndexHelp(const string &T,const string &P,int pos,int next[])
{
int i=pos,j=0;
while(i<T.length()&&j<P.length())
{
//	cout<<"111"<<endl;
if(j==-1)
{
i++;
j=0;
}else if(P[j]==T[i])
{
cout<<"j="<<j<<"i="<<i<<endl;
i++;
j++;
}else
{
j=next[j];
cout<<"j="<<j<<endl;
}
}
cout<<"j="<<j<<endl;
cout<<"P.length()="<<P.length()<<endl;
if(j<0&&P.length()>=0||j<P.length())
{
return -1;
}
else
{
return i-j;
}

}

void getNext(const string &P,int next[])
{
int j=0,k=-1;
next[0]=-1;
while(j<P.length()-1)//应为递推
{
//	cout<<next[j]<<endl;
//	cout<<j<<endl;
if(k==-1)
{
//cout<<"333"<<endl;
next[j+1]=0;
j++;
k=0;
}else if(P[j]==P[k])
{
next[j+1]=k+1;
k++;
j++;
}else
k=next[k];
}
}

int KMPIndex(const string &T,const string &P,int pos=0)
{
int *next=new int[P.length()];
getNext(P,next);
int result=KMPIndexHelp(T,P,pos,next);
delete []next;
return result;
}
void main()
{
cout<<KMPIndex("abbababa","abc",0)<<endl;
}