KMP算法的代码实现

 1 #include <iostream>
 2 #include <string>
 3 #include <iterator>//输出
 4 
 5 using namespace std;
 6 void Next(string str, int next[]){  //自己跟自己匹配
 7     int length=str.size(); 
 8     next[0]=-1;
 9     int j=-1;
10     for(int i=1;i<length;i++){
11         while(j>-1 && str[j+1]!=str[i]) j=next[j];
12         if(str[j+1]==str[i]) j++;
13         next[i]=j;
14     }
15 }
16 void Match(string str1,string str2,int next[]){
17     Next(str2,next);
18     int length1=str1.size(),length2=str2.size();
19     int j=-1;
20     for(int i=0;i<length1;i++){
21         while(j>-1 && str2[j+1]!=str1[i]) j=next[j];
22         if(str2[j+1]==str1[i]) j++;
23         if(j==length2-1){
24             cout<<"Pattern occurs with shift "<<i-length2+1<<endl;
25             j=next[j];
26         }
27     }
28 }
29 int main(){
30    string str1="bbcabcdababcdabcdabde";
31    string str2="abcdabd";
32    int next[20];
33    Match(str1,str2,next);
34    copy(next,next+10,ostream_iterator<int>(cout," "));
35    cout<<endl;
36    return 0;
37 }