POJ 3461：Oulipo

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 28155		Accepted: 11251

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 textT, 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

KMP模板题，没有比这个更模板的了。。。

唯一要提醒自己的是最后模式串和原串走的时候j是一直往前走的，不回头！怎么就记不住，每次都是搞了两层循环，然后TLE，你这么搞之前搞的那个next数组有什么用，动脑袋想一想啊光速小子。

代码：

#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <cstring>
using namespace std;

char moshi[10005];
char pipei[1000005];

int result;
int next_moshi[10005];

void get_next()
{
	int i,j=-1;
	int len=strlen(moshi);
	next_moshi[0]=-1;

	for(i=0;i<len;)
	{
		if(j==-1||moshi[i]==moshi[j])
		{
			i++;
			j++;

			if(moshi[i]==moshi[j])
			{
				next_moshi[i]=next_moshi[j];
			}
			else
			{
				next_moshi[i]=j;
			}
		}
		else
		{
			j=next_moshi[j];
		}
	}
}

void get_result()
{
	int i=0,j=0;

	int len_pipei=strlen(pipei);
	int len_moshi=strlen(moshi);

	while(j<len_pipei)
	{
		if(moshi[i]==pipei[j])
		{
			i++;
			j++;
		}
		else
		{
			if(next_moshi[i]==-1)  
			{  
				i=0;  
				j++;  
			}  
			else  
			{  
				i=next_moshi[i];  
			} 
		}
		if(i>=len_moshi)
		{
			result++;
			i=next_moshi[len_moshi];
		}
	}
}

int main()
{
	int Test;
	scanf("%d",&Test);

	while(Test--)
	{
		result=0;

		scanf("%s%s",moshi,pipei);

		get_next();
		get_result();

		cout<<result<<endl;
	}
	return 0;
}

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