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
Source
#include <iostream>
#include <cstdio>
#include <cstring> using namespace std; char A[+],B[+];
int T[+];
int n,ans; void calc_T()//找到失配函数
{
T[]=-;
int j,lenA=strlen(A);
for (int i=;i<lenA;i++)
{
j=T[i];
while (j!=- && A[j]!=A[i]) j=T[j];
T[i+]=++j;
}
} void kmp(int lenA)
{
calc_T();
int j=,k=,lenB=strlen(B);
while (k<lenB && j<lenA)
{
if (k==- || A[j]==B[k]) j++,k++;
else k=T[k];
if (k==lenB) ans++,k=T[k];
}
//return ans;
} int main()
{
while (~scanf("%d",&n))
{
for (int i=;i<=n;i++)
{
ans=;
scanf("%s%s",B,A);
kmp(strlen(A));
printf("%d\n",ans);
}
}
}
Code