poj 3461

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 40525 Accepted: 16304

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

1
3
其实 一次匹配完成之后 模式串的'\0'会和主串比较 不匹配 然后自动移到合适的地方
#include <iostream>#include<cstdio>#include<cstring>using namespace std;char a[10005],b[1000005];int n[1000005];void kmp(int len){    n[0]=-1;    int k=-1;    int j=0;    while(j<len)    {        if(k==-1||a[j]==a[k])        {            k++;            j++;            n[j]=k;        }        else k=n[k];    }}int main(){    int t;    cin>>t;    while(t--)    {        scanf("%s%s",a,b);        int len1=strlen(a),len2=strlen(b);        kmp(len1);        int flag=0;        for(int i=0,j=0;i<len2;i++)        {            while(j>0&&a[j]!=b[i])j=n[j];            if(a[j]==b[i])j++;            if(j==len1){flag++;}        }        cout<<flag<<endl;            }    return 0;}