KMP算法专题-1001

A - Oulipo

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
***ERDXIVYERDIAN

Sample Output

1
3
0

考点：KMP算法求匹配字符串；

代码：

#include<stdio.h>
#include<string.h>
int next[10005];
char str[1000005],str2[1000005];
int cnt;
void getnext(int len2)
{
	int i=0,j=-1;
	next[0]=-1;
	while(i<len2)
	{
       if(j==-1||str2[i]==str2[j])
	   {
   		i++;j++;
   	     if(str2[i]!=str2[j])
   	      next[i]=j;
         else 
         next[i]=next[j];
	   }		
	   else j=next[j];
	}
}
void kmp(int len1,int len2)
{
	int i=0,j=0;
	getnext(len2);
	while(i<len1)
	{
		if(j==-1||str[i]==str2[j])
	    {
    	  ++i;++j;	
    	}
    	else 
    	j=next[j];
    	if(j==len2)
    	{
	    	cnt++;
	    	j=next[j];
	    }
	}
}
int main()
{
  int n;
  int len1,len2;
  scanf("%d",&n);
  getchar();
  while(n--)
  {
  	gets(str2);
  	gets(str);
  	len1=strlen(str);
    len2=strlen(str2);
    cnt=0;
    kmp(len1,len2);
    printf("%d\n",cnt);
  }	
}