HDU 1686 Oulipo（kmp）

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

3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN

 

Sample Output

130

 

Source

kmp模板

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define N 1000005char a[N],b[N];int ans,next[N];void getfail(char *b){int i,j;int len=strlen(b);next[0]=-1;i=0;j=-1;while(i<len){if(j==-1||b[i]==b[j]){i++;j++;next[i]=j;}elsej=next[j];}}void kmp(char *a,char *b){int i,j;int lena=strlen(a);int lenb=strlen(b);i=j=0;while(i<lena){if(j==-1||a[i]==b[j]){i++;j++;}elsej=next[j];if(j==lenb){ans++;j=next[j];}}}int main(){int i,j,t;scanf("%d",&t);while(t--){scanf("%s%s",b,a);getfail(b);ans=0;kmp(a,b);printf("%d\n",ans);}return 0;}