poj 3461 Oulipo

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 30825 Accepted: 12396

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

解题思路：kmp算法

#include<string.h>#include<stdio.h>char str[1000010],s[10010];int nextval[10010];int m,n;void get_nextval(){int i=0,j=-1;nextval[i]=j;while(i<m){if(j==-1||(s[i]==s[j]))   {     i++;  j++;     if(s[i]!=s[j])         nextval[i]=j;//优化next数组      else  nextval[i]=nextval[j];      }else  j=nextval[j];}}int kmp(){int ant=0;int i=0,j=0;get_nextval();while(i<n){if(j==-1||(str[i]==s[j])){i++;j++;if(j==m)   ant++;}else  j=nextval[j];}return ant;} int main(){int T;scanf("%d",&T);while(T--){int count=0;scanf("%s%s",s,str);m=strlen(s);n=strlen(str);memset(nextval,0,sizeof(nextval));count=kmp();printf("%d\n",count);}return 0;}