【poj 3461】Oulipo（KMP）

 

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 47077		Accepted: 18734

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

 

查找一个模式串在其他串中出现的次数；

 

KMP即可

#include
#include
#include
using namespace std;
#define MAXN 1000050
char s[MAXN];
char t[MAXN];
int l1,l2;
int nxt[MAXN];
void getnxt()
{
	int j,k;
	j=0;
	k=-1;
	nxt[0]=-1;
	while(j0&&s[i]!=t[j])
		{
			j=nxt[j];
		}
		if(s[i]==t[j])
		{
			j++;
		}
		if(j==l2)
		{
			ans++;
			j=nxt[j];
		}
	}
	return ans;
}
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int T;
	cin>>T;
	while(T--)
	{
		cin>>t>>s;
		l1=strlen(s);
		l2=strlen(t);
		cout<