Oulipo
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 49925 | Accepted: 19810 |
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
AVERDXIVYERDIANSample Output
1
3
0思路：
kmp直接套
代码：
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn = (int)1e4 + 5;
const int Maxn = (int)1e6 + 5;
char s1[maxn],s2[Maxn];
int nxt[maxn];
void init(int n)
{
int i = 1,j = 0;
while (i < n)
{
if (s1[i] == s1[j]) nxt[i ++] = ++ j;
else if (!j) i ++;
else j = nxt[j - 1];
}
}
void kmp(int n,int m)
{
int ans = 0,i = 0,j = 0;
while (i < m)
{
if (s1[j] == s2[i])
i ++,j ++;
else if (!j) i ++;
else j = nxt[j - 1];
if (j == n) ans ++;
}
printf("%d\n",ans);
}
int main()
{
int t;
scanf("%d",&t);
while (t --)
{
scanf("%s %s",s1,s2);
int n = strlen(s1),m = strlen(s2);
init(n);
kmp(n,m);
}
return 0;
}