HDU 1686

Description
The French author Georges Perec (1936�1982) once wrote a book, La disparition, without the letter 'e'. He was a member of the Oulipo group. A quote from the book:


Tout avait Pair normal, mais tout s’affirmait faux. Tout avait Fair normal, d’abord, puis surgissait l’inhumain, l’affolant. Il aurait voulu savoir où s’articulait l’association qui l’unissait au roman : stir son tapis, assaillant à tout instant son imagination, l’intuition d’un tabou, la vision d’un mal obscur, d’un quoi vacant, d’un non-dit : la vision, l’avision d’un oubli commandant tout, où s’abolissait la raison : tout avait l’air normal mais…


Perec would probably have scored high (or rather, low) in the following contest. People are asked to write a perhaps even meaningful text on some subject with as few occurrences of a given “word” as possible. Our task is to provide the jury with a program that counts these occurrences, in order to obtain a ranking of the competitors. These competitors often write very long texts with nonsense meaning; a sequence of 500,000 consecutive 'T's is not unusual. And they never use spaces.


So we want to quickly find out how often a word, i.e., a given string, occurs in a text. More formally: given the alphabet {'A', 'B', 'C', …, 'Z'} and two finite strings over that alphabet, a word W and a text T, count the number of occurrences of W in T. All the consecutive characters of W must exactly match consecutive characters of T. Occurrences may overlap.


 
Input
The first line of the input file contains a single number: the number of test cases to follow. Each test case has the following format:


One line with the word W, a string over {'A', 'B', 'C', …, 'Z'}, with 1 ≤ |W| ≤ 10,000 (here |W| denotes the length of the string W).
One line with the text T, a string over {'A', 'B', 'C', …, 'Z'}, with |W| ≤ |T| ≤ 1,000,000.
 
Output
For every test case in the input file, the output should contain a single number, on a single line: the number of occurrences of the word W in the text T.


 
Sample Input
3
BAPC
BAPC
AZA
AZAZAZA
VERDI
AVERDXIVYERDIAN
 
Sample Output
1
3

0

这也是用KMP算法实现的,代码:

#include<iostream>#include<string>using namespace std;char F[10010010];char S[10010];int next[10010];int lenF;int lenS;void getnext(){     int i=1;     int j=0;     next[1]=0;     while(i<=lenS)     {         if(j==0||S[i]==S[j])         {             i++;             j++;             if(S[i]!=S[j])             next[i]=j;             else next[i]=next[j];         }         else         {            j=next[j];          }     } } void kmp(){     int i=1;     int j=1;     int count=0;     while(i<=lenF&&j<=lenS)     {         if(j==0||F[i]==S[j])         {             i++;             j++;         }         else          {             j=next[j];         }         if(j>lenS)         {             count++;             j=next[j];         }     }     cout<<count<<endl; } int main() {     int t;     cin>>t;     while(t--)     {         cin>>S+1;         cin>>F+1;         lenS=strlen(S+1);         lenF=strlen(F+1);         getnext();         kmp();     } return 0; }