【POJ 3461】Oulipo

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 55633		Accepted: 21703

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

题目大意：给你两个字符串p和s，求出p在s中出现的次数，求的是主串和子串的匹配问题。

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
typedef long long ll;
using namespace std;
const int N=100010;
char s[N * 10], p[N];
int nextval[N];
int lens, lenp;
void getnext(){
    int i=0,j=-1;
    nextval[0]=-1;
    while(i!=lenp){
        if(j==-1||s[i]==s[j])
            nextval[++i]=++j;
        else
            j=nextval[j];
    }
}
 
int KMP(){
    int i=0,j=0,count=0;
    while(i != lens && j != lenp){
        if(s[i] == p[j] || j == -1)
            ++i, ++j;
        else
            j = nextval[j];
        if(j == lenp){
            count++;
            j = nextval[j];
        }
    }
    return count;
}
 
int main(){
    freopen("3461.in","r",stdin);
    freopen("3461.out","w",stdout);
    int ncase;
    int len;
    int ans;
    scanf("%d", &ncase);
    while(ncase--){
        scanf("%s%s", p, s);
        lens=strlen(s);
        lenp=strlen(p);
        getnext();
        ans=KMP();
        printf("%d
", ans);
    }
    return 0;
}