kmp hdu 1686

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): 31930    Accepted Submission(s): 12181

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<cstdio>
#include<cstring>
const int maxw=10000+3;
const int maxt=1000000+3;
int cas;
char w[maxw],t[maxt];
int next[maxw];
int sum;
int i,j,k;
int main(){
    scanf("%d",&cas);
    getchar();
    while(cas--){
        //printf("!!!!!\n");
        gets(w);
        gets(t);
        
        int lenw=strlen(w);
        int lent=strlen(t);
        k=-1;
        next[0]=-1;
        j=0;
        while(j<lenw){
            if(k==-1||w[j]==w[k]){
                k++;
                j++;
                if(w[j]!=w[k]){
                    next[j]=k;
                }else{
                    next[j]=next[k];
                }
            }else{
                k=next[k];
            }
        }
    //    printf("#### %d\n",next[lenw]);
        j=0,i=0;
        sum=0; 
        while(i<lent){
            if(j==-1||w[j]==t[i]){
            //    printf("%d %d\n",j,i);
                if(j==lenw-1&&w[j]==t[i]){
                    sum++;
                }
                if(j==lenw){
                    j=next[j];//next[j]表示在第j个字符之前的 从0到j-1的字符串中的最大相同前后缀的值； 
                }
                j++;
                i++;
            }else{
                j=next[j];
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}