HDU1686Oulipo KMP返回串出现的次数

http://acm.hdu.edu.cn/showproblem.php?pid=1686

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

#include <stdio.h>
#include <string.h>
int next[10005];
char str1[1000005],str2[10005];
void getnext(int len)//此处也可以将int next[]改写成  int* next[]
{
    int j,k;
    j=0,k=-1;
    next[0]=-1;
    while(j<len)
    {
        if(k==-1||str2[j]==str2[k])
        {
            j++,k++,next[j]=k;
        }
        else
        {
            k=next[k];
        }
    }
    //利用待匹配串进行求解next数组
}
int kmp(int len1,int len2)//kmp算法
{
    int count=0;
    int i=0,j=0;
    getnext(len2);
    while(i<len1)//是文本串长度;
    {
        if(j==-1||str1[i]==str2[j])
        {
            ++i,++j;
        }
        else
        {
            j=next[j];
        }
        if(j==len2)
        {
            count++;
            j=next[j];
        }
    }
    return count;

}
int main()
{
    int Case;
    int len1,len2;
    scanf("%d",&Case);
    getchar();//注意吸收空格
    while(Case--)
    {
        gets(str2);
        gets(str1);
        len1 = strlen(str1), len2 = strlen(str2);
        printf("%d\n",kmp(len1,len2));
    }
    return 0;
}

HDU1686Oulipo KMP返回串出现的次数

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