Oulipo
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 35726 | Accepted: 14436 |
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 <iostream>
#include <stdio.h>
#include <algorithm>
#include <string.h>
using namespace std;
const int maxn=1000010;
char s[maxn],w[10010];
int next[10010];
void get_next(int l) //求next数组函数
{
int i=0,j=-1;
next[0]=-1;
while(i<l)
{
if(j==-1||w[i]==w[j])
{
i++;
j++;
next[i]=j;
}
else
j=next[j];
}
}
int kmp()
{
int l1=strlen(s),l2=strlen(w);
get_next(l2);
int i=0,j=0,ans=0;
while(i<l1)
{
if(j==-1||s[i]==w[j])
{
i++;
j++;
}
else
j=next[j];
if(j==l2)
{
ans++;
j=next[j]; //若两个不同的匹配没有交集则j=0,若存在交集则j=next[j];
}
}
return ans;
} //以上部分相当于模板
int main()
{
int n;
scanf("%d",&n);
while(n--)
{
scanf("%s %s",w,s);
int ans=kmp();
printf("%d\n",ans);
}
return 0;
}