【KMP】Oulipo POJ3461

Oulipo

Time Limit: 1000MS

Memory Limit: 65536K

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

题目大意：

给你A串和B串，求出A串在B串中出现的次数

KMP裸题，第一次写KMP，有点生疏，继续加油~

测评情况（POJ）

C++ AC Code

#include<cstdio>
#include<cstring>
const int N=1000000+10;
char t[N],s[N];//模式和串
int tlen,slen;//对应长度
int next[N];

void getnext()
{
	memset(next,0,sizeof(next));
	next[0]=-1;
	int j=0,k=-1;
	while(j<tlen)
	{
		if(k==-1||t[j]==t[k]) next[++j]=++k;
		else k=next[k];
	}
}

int solve()
{
	int res=0;
	getnext();
	int i=0,j=0;
	while(i<slen)
	{
		if(j==-1||s[i]==t[j]) {i++;j++;}
		else j=next[j];
		if(j==tlen) res++;
	}
	return res;
}

void work()
{
	memset(t,0,sizeof(t));
	memset(s,0,sizeof(s));
	scanf("%s\n%s\n",t,s);
	tlen=strlen(t);slen=strlen(s);
	printf("%d\n",solve());
}


int main()
{
	freopen("poj3461.in","r",stdin);
	freopen("poj3461.out","w",stdout);
	int grp;scanf("%d\n",&grp);
	while(grp--) work();
	return 0;
}