hdu1686 Oulipo（KMP）

Oulipo

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

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 4041    Accepted Submission(s): 1595

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

#include<stdio.h>
#include<string.h>
int next[10004];
char t[10004],s[1000004];
void get_nextval(int len)
{
    int i=0,k=-1;
    next[0]=-1;
    while(i<len)
        if(k==-1||t[i]==t[k])
        {
            ++i;
            ++k;
            if(t[i]!=t[k])
                next[i]=k;
            else
                next[i]=next[k];
        }
        else
            k=next[k];
}
int KMP(int ls,int lt)
{
    get_nextval(lt);
    int i=0,j=0,ans=0;
    while(i<ls)
        if(s[i]==t[j])
        {
            i++;
            j++;
            if(j==lt)
            {
                ans++;
                j=next[j];
            }
        }
        else
        {
            if(next[j]!=-1)
                j=next[j];
            else
            {
                j=0;
                i++;
            }
        }
    return ans;
}
int main()
{
    int cas,lt,ls,ans,i;
    scanf("%d",&cas);
    while(cas--)
    {
        memset(next,0,sizeof(next));
        scanf("%s%s",t,s);
        lt=strlen(t);
        ls=strlen(s);
        ans=KMP(ls,lt);
        printf("%d\n",ans);
    }
    return 0;
}