KMP 水水

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>

using namespace std;
#define maxn 400000 + 10
int len, next[maxn], cnt = 0;
int L;
string s1, s;

void getnext()
{
     int i = 0; 
     int j =  -1;
     next[0] = -1;
     while(i < len)   
     {
         if(j == -1 || s[i] == s[j])
         {
              i++, j++;
              next[i] = j;     
         }    
         else j = next[j];
     }  
}

void kmp()
{
         int i = 0; 
         int j = 0;
         cnt = 0;
         getnext();
         while(i < L)
         {
              if(j == -1 || s1[i] == s1[j])
              {
                  i++; j++;     
              }    
              else j = next[j];
              if(j == len)
              {
                  cnt++;   
                  j = next[j];  
              }    
         } 
}

int main()
{
    cin>>s>>s1;
    len = s.size();
    L = s1.size();
    kmp();
    cout<<cnt<<endl;
    system("pause");
    return 0;
}

KMP 水水

原文：http://blog.csdn.net/dojintian/article/details/44982679