【poj3461】Oulipo 【BAPC 2006 Qualification】

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 wordW and a text T, count the number of occurrences of W inT. All the consecutive characters of W must exactly match consecutive characters ofT. 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 stringW).
• 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 wordW in the text T.

Sample Input

3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN

Sample Output

130

这道题标解是KMP，但是用hash就可以过，下面是程序：

#include<stdio.h>#include<string.h>#include<iostream>#define ll unsigned long long using namespace std;ll hash[1000005],x,cf[1000005];char a[1000005];void read(ll &s,int &l){s=l=0;char c=getchar();while(!(c>='A'&&c<='Z')){c=getchar();}while(c>='A'&&c<='Z'){l++;s*=27;s+=c-'A'+1;c=getchar();}}ll ask(int i,int j){return hash[j]-hash[i-1]*cf[j-i+1];}void work(){int i,l1,l2,s=0;read(x,l1);scanf("%s",a+1);l2=strlen(a+1);hash[1]=a[1]-'A'+1;for(i=2;i<=l2;i++){hash[i]=hash[i-1]*27+a[i]-'A'+1;}for(i=1;i<=l2-l1+1;i++){if(ask(i,i+l1-1)==x){s++;}}printf("%d\n",s);}int main(){int t,i;for(cf[0]=1,i=1;i<=1000000;i++){cf[i]=cf[i-1]*27;}scanf("%d",&t);while(t--){work();}return 0;}