HDU 1686：Oulipo

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

 

分析：

還是KMP，稍微有變形，找到長串中模板串的個數，要注意的一點是可重複匹配，就是說abcdabcdabcd中：abcdabcdabcd   abcdabcdabcd  

所以這個算兩個。

代碼：

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
char A[10005];
char B[1000005];
int nxt[10005];
int n,m,t;

int makenext()
{
    int l,r;
    l=-1;r=0;nxt[0]=-1;
    while(r<m){
        if(l==-1||A[l]==A[r]){
            nxt[++r]=++l;
        }else{
            l=nxt[l];
        }
    }
}

int kmp()
{
   makenext();
   int ans=0;
   int ln=0,lm=0;
    while(ln<n){
        if(lm==-1||B[ln]==A[lm]){
            ++ln;++lm;
        }else{
            lm=nxt[lm];
        }
        if(lm>=m){
            ++ans;
            lm=nxt[lm];
        }
    }
    return ans;
}

int main()
{
  //  freopen("in.txt","r",stdin);
    scanf("%d",&t);
    bool dec;
    while(t--){
        dec=true;
        memset(nxt,0,sizeof(nxt));
        scanf("%s%s",&A,&B);
        n=strlen(B);
        m=strlen(A);
        printf("%d\n",kmp());
    }
    return 0;
}