poj3461 Oulipo(KMP模板)

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 17795		Accepted: 7160

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

 

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int next[10005];
void getnext(char str[]) {
    int j = 0;
    int k = -1;
    next[0] = -1;
    int len = strlen(str);
    while (j < len) {
        if (k == -1 || str[j] == str[k]) {
            j++;
            k++;
            if (str[j] == str[k])
                next[j] = next[k];
            else
                next[j] = k;
        } else {
            k = next[k];
        }
    }
}
int kmp(char p[], char s[]) {
    getnext(p);
    int j = 0;
    int k = 0;
    int ans = 0;
    int plen = strlen(p);
    int slen = strlen(s);
    while (j < slen) {
        if (k == -1 || s[j] == p[k]) {
            j++;
            k++;
        } else {
            k = next[k];
        }
        if (k == plen) {
            ans++;
            k = next[k];
        }
    }
    return ans;
}
int main() {
//    freopen("in.txt","r",stdin);
    int T;
    char s[1000005];
    char p[10005];//模式串
    scanf("%d",&T);
    while (T--) {
        scanf("%s",p);
        scanf("%s",s);
        printf("%d\n",kmp(p,s));
    }
    return 0;
}