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AC日记——Oulipo poj 3461

Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 37958 Accepted: 15282

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

130

Source

BAPC 2006 Qualification
 
 
思路:
  不说了,说多了都是笑>.<;
 
 
来,上代码:
#include <cstdio>#include <string>#include <cstring>#include <iostream>#include <algorithm>using namespace std;int ls,lt,T,next[1000001];char s[1000001],t[1000001];inline void GetNext(){    //memset(next,0,sizeof(next));    int k=-1,j=0;    next[j]=k;    while(j<lt)    {        if(k==-1||t[j]==t[k])        {            k++,j++;            next[j]=k;        }        else k=next[k];    }}inline int Kmp(){    GetNext();    int i=0,j=0,return_=0;    while(i<ls)    {        if(j==-1||s[i]==t[j]) i++,j++;        else j=next[j];        if(j==lt)        {            j=next[j];            return_++;        }    }    return return_;}int main(){    scanf("%d",&T);    for(int i=1;i<=T;i++)    {        cin>>t;        cin>>s;        ls=strlen(s);        lt=strlen(t);        cout<<Kmp()<<endl;    }    return 0;}

 

AC日记——Oulipo poj 3461