poj 3461 Oulipo （求匹配字符串的个数）（KMP）

Oulipo 文本匹配挑战

最新推荐文章于 2019-08-09 10:46:38 发布

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本文介绍了一个基于法国文学团体 Oulipo 的文本匹配竞赛背景的编程挑战，任务是设计一个快速算法来计算给定单词在一个长文本中出现的次数，包括重叠的情况。示例展示了输入输出样例，并提供了完整的 C 语言实现代码。

Oulipo

Time Limit : 3000/1000ms (Java/Other) Memory Limit : 32768/32768K (Java/Other)

Total Submission(s) : 91 Accepted Submission(s) : 57

Problem 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

#include<stdio.h>
#include<string.h>
#define M 1000010
char str[M],buf[M];
int n,m,len1,len2;
int cnt;
int p[M];
void getp()
{
	int i=0,j=-1;
	p[i]=j;
	while(i<len2)
	{
		if(j==-1||str[i]==str[j])
		{
			i++;j++;
			p[i]=j;
		}
		else  j=p[j];	
	}
}
void kmp()
{
	int i=0,j=0;
	while(i<len2)
	{
		if(j==-1||buf[i]==str[j])
		{
			i++;j++;
			if(j==len1) 
			cnt++;
		}
		else  j=p[j];
		
	}
}
int main()
{
	scanf("%d",&n);
	while(n--)
	{
		cnt=0;
		scanf("%s%s",str,buf);
		len1=strlen(str);
		len2=strlen(buf);
		getp();
		kmp();
		printf("%d\n",cnt);			
	}	
	return 0;
}