【字符串匹配】Oulipo

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本文深入探讨了深度学习在自然语言处理领域的应用，包括词法分析、语义理解、文本生成等关键技术，以及如何利用这些技术进行高效的数据处理与分析。

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Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 13672		Accepted: 5499

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

Source

BAPC 2006 Qualification

我们要找到所有的匹配，所以匹配成功之后继续匹配下去就行了。j = next[j];

#include <cstdio>
#include <cstring>
#include <string>

char a[10010];
char b[1000010];
long next[10010];

long ans = 0;

void get_next(char* str)
{
	long j = 1;
	long k = 0;

	long len = strlen(a+1);
	while (j < len+1)
	{
		if (k==0||str[j]==str[k])
		{
			k ++;j ++;
			next[j] = k;
		}
		else k = next[k];
	}
}
void kmp(char* str1,char* str2)
{
	get_next(str2);
	long l1 = strlen(str1+1);
	long l2 = strlen(str2+1);

	long i = 1;
	long j = 1;
	while (i<l1+1 && j<l2+1)
	{
		if (j==0||str1[i]==str2[j])
		{
			i ++;j ++;
		}
		else j = next[j];
		if (j > l2)
		{
			ans ++;
			j = next[j];
		}
	}
}

int main()
{
	freopen("oulipo.in","r",stdin);
	freopen("oulipo.out","w",stdout);
	long n;
	scanf("%ld",&n);
	for (long i=1;i<n+1;i++)
	{
		memset(next,0,sizeof next);
		ans = 0;
		scanf("%s%s",a+1,b+1);
		kmp(b,a);
		printf("%ld\n",ans);
	}
	return 0;
}