POJ 3461 Oulipo

最新推荐文章于 2019-08-09 10:46:38 发布

原创最新推荐文章于 2019-08-09 10:46:38 发布 · 164 阅读

0 ·

CC 4.0 BY-SA版权

POJ 同时被 2 个专栏收录

16 篇文章

订阅专栏

KMP

9 篇文章

订阅专栏

本文介绍了一种用于查找字符串中特定模式出现次数的高效算法——KMP算法，并通过一个具体的编程实例展示了如何实现该算法。

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 44717		Accepted: 17890

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

题意：找上面的字符串在下面的字符串中出现了几次；

思路：kmp模板。。。。

下面附上我的代码：

#include<cstdio>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
string s1,s2;
int next[10005];
void Getnext(string s2,int len)
{
	int i=0;int j=-1;
	next[i]=j;
	while(i<len)
	{
		if(j==-1||s2[i]==s2[j])
		{
			next[++i]=++j;
		}
		else
			j=next[j];
	}
}
int kmp(string s1,int l1,string s2,int l2)
{
	int i=0,j=0,sum=0;
	while(i<l1)
	{
		if(j==-1||s1[i]==s2[j])
		{
			++i;
			++j;
			if(j==l2)
			{	 
				sum++;
			} 
		}
		else 
			j=next[j];
		
	}
	return sum;
}
int main()
{
	int n;
	cin>>n;
	while(n--)
	{
		cin>>s2>>s1;
		int l1=s1.size() ;
		int l2=s2.size() ;
		Getnext(s2,l2);
		printf("%d\n",kmp(s1,l1,s2,l2));
	}
	return 0;
}