POJ Oulipo

http://poj.org/problem?id=3461

 

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 12988		Accepted: 5206

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

Source

BAPC 2006 Qualification

 

标准的KMP匹配模版

 

#include<stdio.h>
char s[1001000],t[10010];
int next[10010] ;
void getnext(){
    int i = 1 , j = 0;
    while(t[i]){
        while(j > 0 && t[i] != t[j])
            j = next[j] ;
        next[++i] = ++j ;
    }
}
void KMP(){
    int ans = 0 ,i = 1 , j = 1 ;
    while(s[i]){
        while(j > 0 && s[i] != t[j] )
            j = next[j] ;
        ++i, ++j;
        if(t[j] == 0)
            ans++ , j = next[j] ;
    }
    printf("%d\n",ans) ;
}
int main(){
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%s%s",&t[1],&s[1]);
        getnext();
        KMP();
    }
    return 0;
}