Oulipo(hash 模板)

#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
using namespace std; 
typedef unsigned long long ull;//ull具有自我取模的特性 
#define mod 1000000007
ull c[10009],sumb[1000008];
char a[10010],b[1000010];  
int main()
{
	int q;
	scanf("%d",&q);
	while(q--)
	{
		scanf("%s",a );
		scanf("%s",b);
		int lena=strlen(a);
		int lenb=strlen(b);
		 ull suma=0;
		 ull p= 100000000+7,q1=1; 

		for(int i=0;i<lena;i++)
		{
			q1=q1*p;
			suma=(suma*p+a[i]-65);
		}  
		int t=0;
		 sumb[0]=b[0]-65;
		for(int i=1;i<lenb ;i++)
		{
		 	sumb[i]=sumb[i-1]*p+b[i]-65 ;
				 
		}
		if(sumb[lena-1]==suma) t++;
		 ull r;
		for(int i=lena;i<lenb;i++)
		{
			r=sumb[i]-sumb[i-lena]*q1;//注意q1的大小,还有别把q1忘了乘。 
			if(r==suma) t++;
		}
	 
		printf("%d\n",t); 
		
	}
	return 0;
}

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

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转载自blog.csdn.net/qq_42434171/article/details/81779930