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

3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN 

 

Sample Output

130 

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);  }}