POJ 3461 Oulipo

r囧r小猫 2022-08-21 11:58 149阅读 0赞

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

kmp裸题

#include<stdio.h>
    #include<string.h>
    #include<algorithm>
    using namespace std;
    char a[1000005],b[1000005];
    int nxt[1000005];
    int cnt;
    void get_nxt()
    {
    	int i=0;
    	int j=-1;
    	nxt[0]=-1;
    	int l=strlen(a);
    	while(i<l)
    	{
    		if(j==-1||a[i]==a[j])
    		{
    			i++;
    			j++;
    			nxt[i]=j;
    		}
    		else
    			j=nxt[j];
    	} 
    }
    int kmp()
    {
    	int l1=strlen(b);
    	int l2=strlen(a);
    	int i,j;
    	i=0;
    	j=0;
    	while(i<l1)
    	{
    		if(j==-1||b[i]==a[j])
    		{
    			i++;
    			j++;
    		}
    		else
    			j=nxt[j];
    		if(j==l2)
    		{
    			cnt++;
    			j=nxt[j];
    		}
    		
    	}
    	return cnt;
    }
    int main()
    {
    	int i,j,k,m,n,l;
    	while(~scanf("%d",&n))
    	{
    		while(n--)
    		{
    			cnt=0;
    			memset(nxt,0,sizeof(nxt));
    			scanf("%s %s",a, b);
    			int l1=strlen(a);
    			int l2=strlen(b);
    		//	for(i=0;i<l1;i++)
    		//	{
    		//		printf("%d\n",nxt[i]);
    		//	}
    			get_nxt();
    			kmp();
    			printf("%d\n",cnt);
    		}
    	}
    	return 0;
    }