扩展KMP算法

 1 #include<iostream>  
 2 #include<string>  
 3 #include<cstdio>
 4 using namespace std;  
 5 const int MM=100005;  //长度最大值 
 6 int next[MM],extand[MM];  
 7 char S[MM],T[MM];  
 8 void GetNext(const char *T){  
 9      int len=strlen(T),a=0;  
10      next[0]=len;  
11      while(a<len-1 && T[a]==T[a+1]) a++;  
12      next[1]=a;  
13      a=1;  
14      for(int k=2;k<len;k++){  
15          int p=a+next[a]-1,L=next[k-a];  
16          if( (k-1)+L >= p){  
17              int j = (p-k+1)>0 ? (p-k+1) : 0;  
18              while(k+j<len && T[k+j]==T[j]) j++;  
19              next[k]=j;  
20              a=k;   
21          }   
22          else  
23              next[k]=L;   
24      }   
25 }   
26 void GetExtand(const char *S,const char *T){  
27      GetNext(T);  
28      int slen=strlen(S),tlen=strlen(T),a=0;   
29      int MinLen = slen < tlen ? slen : tlen;  
30      while(a<MinLen && S[a]==T[a]) a++;  
31      extand[0]=a;  
32      a=0;  
33      for(int k=1;k<slen;k++){  
34          int p=a+extand[a]-1, L=next[k-a];  
35          if( (k-1)+L >= p){  
36              int j= (p-k+1) > 0 ? (p-k+1) : 0;  
37              while(k+j<slen && j<tlen && S[k+j]==T[j]) j++;  
38              extand[k]=j;  
39              a=k;   
40          }  
41          else   
42              extand[k]=L;   
43      }   
44 }   
45 int main(){  
46     while(scanf("%s%s",S,T)==2){  
47          GetExtand(S,T);  
48          for(int i=0;i<strlen(T);i++)  
49              printf("%d ",next[i]);  
50          puts("");  
51          for(int i=0;i<strlen(S);i++)  
52              printf("%d ",extand[i]);  
53          puts("");   
54     }   
55     return 0;  
56 }