// exam1.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
using namespace std;

void get_next(int* &next,char* s)
{
	int j=0;
	int i=1;

	int len=strlen(s);
	next=(int*)malloc(len*sizeof(int));
	memset(next,len*sizeof(int));

	while(s[i]!='\0')
	{
		if(s[j]==s[i])
		{
			i++;
			j++;
			if(s[i]!=s[j])
			{
				next[i]=j;
			}
			else
			{
				next[i]=next[j];
			}
		}
		else
		{
			if(j==0)
			{
				i++;
			}
			j=next[j];
		}
	}
}

int kmp(int* next,char* s,char* m)
{
	int i=0,j=0;

	while(s[i]!='\0')
	{
		if(m[j]=='\0')
		{
			break;
		}
		if(s[i]==m[j])
		{
			i++;
			j++;
		}
		else
		{
			if(j==0)
			{
				i++;
			}
			j=next[j];
		}
	}

	return i-strlen(m);
}

int main(void)
{
	int len,*next;
	char *s="acabaabaabcacaabc";
	char *m="abaabcac";
	len=strlen(m);

	get_next(next,m);
	int loc=kmp(next,s,m);

	/*for(int i=0;i<len;i++)
	{
		cout<<next[i]<<endl;
	}*/
	cout<<loc<<endl;

	system("pause");
	return 0;
}

code2

#include "stdafx.h"
#include <iostream>
#include <string>
#include <stack>
using namespace std;


void getNext(char* s,int* &next)
{
<span style="white-space:pre">	</span>next=new int[strlen(s)];
<span style="white-space:pre">	</span>memset(next,strlen(s)*sizeof(int));


<span style="white-space:pre">	</span>int i=0;
<span style="white-space:pre">	</span>int j=-1;
<span style="white-space:pre">	</span>next[0]=-1;


<span style="white-space:pre">	</span>while(i<strlen(s))
<span style="white-space:pre">	</span>{
<span style="white-space:pre">		</span>if(j==-1 || s[i]==s[j])
<span style="white-space:pre">		</span>{
<span style="white-space:pre">			</span>i++;
<span style="white-space:pre">			</span>j++;
<span style="white-space:pre">			</span>if(s[i]==s[j])
<span style="white-space:pre">			</span>{
<span style="white-space:pre">				</span>next[i]=next[j];
<span style="white-space:pre">			</span>}
<span style="white-space:pre">			</span>else
<span style="white-space:pre">			</span>{
<span style="white-space:pre">				</span>next[i]=j;
<span style="white-space:pre">			</span>}
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>else
<span style="white-space:pre">		</span>{
<span style="white-space:pre">			</span>j=next[j];
<span style="white-space:pre">		</span>}
<span style="white-space:pre">	</span>}
}


void kmp(char* s,char* t,int* next)
{
<span style="white-space:pre">	</span>int i=0;
<span style="white-space:pre">	</span>int j=0;
<span style="white-space:pre">	</span>
<span style="white-space:pre">	</span>int len1=strlen(s);
<span style="white-space:pre">	</span>int len2=strlen(t);


<span style="white-space:pre">	</span>while(i<len1 && j<len2)
<span style="white-space:pre">	</span>{
<span style="white-space:pre">		</span>if(j==-1 || s[i]==t[j])
<span style="white-space:pre">		</span>{
<span style="white-space:pre">			</span>i++;
<span style="white-space:pre">			</span>j++;
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>else
<span style="white-space:pre">		</span>{
<span style="white-space:pre">			</span>j=next[j];
<span style="white-space:pre">		</span>}
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>if(j==strlen(t))
<span style="white-space:pre">	</span>{
<span style="white-space:pre">		</span>cout<<s+i-strlen(t)<<endl;
<span style="white-space:pre">	</span>}
}


int main(void)
{
<span style="white-space:pre">	</span>char* s="acabaabaabcacaabc";
<span style="white-space:pre">	</span>char* t="abaabcac";
<span style="white-space:pre">	</span>int* next;


<span style="white-space:pre">	</span>getNext(t,next);
<span style="white-space:pre">	</span>kmp(s,t,next);




<span style="white-space:pre">	</span>system("pause");
<span style="white-space:pre">	</span>return 0;
}