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  • HDU 1686 Oulipo(kmp)

    Problem 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


    kmp模板


    #include <iostream>
    #include <cstdio>
    #include <cstring>
    #include <algorithm>
    
    using namespace std;
    #define N 1000005
    
    char a[N],b[N];
    int ans,next[N];
    
    void getfail(char *b)
    {
    	int i,j;
    	int len=strlen(b);
    	next[0]=-1;
    	i=0;j=-1;
    	while(i<len)
    	{
    		if(j==-1||b[i]==b[j])
    		{
    			i++;
    			j++;
    			next[i]=j;
    		}
    		else
    			j=next[j];
    	}
    }
    
    void kmp(char *a,char *b)
    {
    	int i,j;
    	int lena=strlen(a);
    	int lenb=strlen(b);
    	i=j=0;
    	while(i<lena)
    	{
    		if(j==-1||a[i]==b[j])
    		{
    			i++;
    			j++;
    		}
    		else
    			j=next[j];
    
    		if(j==lenb)
    		{
    			ans++;
    			j=next[j];
    		}
    	}
    }
    
    int main()
    {
    	int i,j,t;
    	scanf("%d",&t);
    	while(t--)
    	{
    		scanf("%s%s",b,a);
    		getfail(b);
    		ans=0;
    		kmp(a,b);
    		printf("%d
    ",ans);
    	}
    	return 0;
    }
    






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  • 原文地址:https://www.cnblogs.com/mengfanrong/p/4238439.html
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