POJ 3461 Oulipo kmp 水过

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
AVERDXIVYERDIAN

Sample Output

1
3
0

Source

BAPC 2006 Qualification

C风格的输入节省时间

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#define maxw 10000+1
#define maxt 1000000+1
using namespace std;
char word[maxw];
char text[maxt];
int suffix[maxw];
int lenw,lent;
int kmp(){
    int cns=0;
    int posw=0,post=0;
    ///cout<<"lent: "<<lent<<'\12';
    while(post<lent){
        if(word[posw]==text[post]){
            posw++;
            post++;
        }
        else if(posw>=0){
            posw=suffix[posw];
        }
        else {
            post++;
            posw=0;
        }
        if(posw==lenw){
            cns++;
            posw=suffix[posw];
        }
    }
    return cns;
}
int main(){
    int loop;
    scanf("%d",&loop);
    while(loop--){
        scanf("%s%s",word,text);
        lent=strlen(text);
        lenw=strlen(word);
        int pos=0,i,j;
        suffix[0]=-1;
        suffix[1]=0;
        for( i=2;i<=lenw;++i){
            while(pos>=0&&word[pos]!=word[i-1])
                pos=suffix[pos];
            suffix[i]=++pos;
        }
        ///for(j=0;j<i;++j)cout<<"suffix["<<j<<"]: "<<suffix[j]<<'\12';
        printf("%d\n",kmp());
    }
    return 0;
}

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