bzoj3620 似乎在梦中见过的样子

好久没有写过KMP了，今天写个KMP练练手。
此题就是枚举左端点暴力，用KMP做到O（n^2）

 #include<cstdio>
 #include<cstring>
 using namespace std ; 

 const int MAXL =  +  ;

 char BUF_OF_T [ MAXL ] ;
 int BUF_OF_F [ MAXL ] ;

 class KMP {
     private :
         char * T ;
         int * F ;
     public :
         KMP ( char * S ) {
             const int L = strlen ( S ) ;
             T = BUF_OF_T ; F = BUF_OF_F ;
             strcpy ( T , S ) ; F [  ] = - ;
             for ( int i =  ; i <= L ; ++ i ) {
                 int p = F [ i -  ] ;
                 while ( p >=  && T [ i ] != T [ p +  ] ) p = F [ p ] ;
                 F [ i ] = T [ i ] == T [ p +  ] ? p +  : - ;
             }
         }
         int * GET_FAIL () const { return F ; }
 } ; 

 char S [ MAXL ] ;
 int K ;
 int cnt ;
 int main () {
     scanf ( "%s%d" , S , & K ) ;
     for ( int i =  ; S [ i ] != '\0' ; ++ i ) {
         char * a = S + i ;
         KMP D ( a ) ;
         int * next = D . GET_FAIL () ;
         const int L = strlen ( a ) ;
         for ( int j =  ; j <= L ; ++ j ) { //重点：是1 <= j <= L 不是 1 <= j < L
             int & p = next [ j ] ;
             while ( p != - && next [ p ] +  >= K ) p = next [ p ] ;
             if ( p +  >= K && j +  - ( p +  ) *  >  ) cnt ++ ;
         }
     }
     printf (  "%d\n" , cnt ) ;
     return  ;
 }