hdu 1686 Oulipo KMP算法

最新推荐文章于 2023-11-06 10:43:58 发布

hpugym

最新推荐文章于 2023-11-06 10:43:58 发布

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分类专栏： KMP

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本文介绍了一个基于字符串匹配的比赛任务，旨在快速计算给定单词在特定文本中出现的次数，包括重叠情况。文章提供了算法实现示例，利用 KMP 算法中的 next 函数来高效解决这一问题。

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Oulipo

Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5594 Accepted Submission(s): 2238

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

Source

华东区大学生程序设计邀请赛_热身赛

//关键是Nex()t函数的运用

#include<stdio.h>
#include<string.h>
#define M 10010
#define N 1000010
int next[M];
char str1[M],str2[N];
void get_next()
{
    int  i=0, j=-1;
    int  len=strlen(str1);
     next[0]=-1;
    while(i<len)
    {
        if(j==-1||str1[i]==str1[j])
        {
            i++;
            j++;
            next[i]=j;
        }
        else
        j=next[j];
    }
}
int kmp()
{
    get_next();
    int i,j;
	int num,len1,len2;
     i=j=num=0;
    len1=strlen(str1);
    len2=strlen(str2);
    while(i<len2)
    {
        if(j==-1||str2[i]==str1[j])
        {
            i++;
            j++;
        }
        else
           j=next[j];
         if(j==len1)
         {
             ++num;
             j=next[j];
         }
    }
    return num;
}
int main()
{
    int n;
    int sum;
    scanf("%d",&n);
    while(n--)
    {
       memset(str1,0,sizeof(str1));
       memset(str2,0,sizeof(str2));
        scanf("%s%s",str1,str2);
        sum=kmp();
        printf("%d\n",sum);
    }return 0;
}