Oulipo
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 17795 | Accepted: 7160 |
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;
int next[10005];
void getnext(char str[]) {
int j = 0;
int k = -1;
next[0] = -1;
int len = strlen(str);
while (j < len) {
if (k == -1 || str[j] == str[k]) {
j++;
k++;
if (str[j] == str[k])
next[j] = next[k];
else
next[j] = k;
} else {
k = next[k];
}
}
}
int kmp(char p[], char s[]) {
getnext(p);
int j = 0;
int k = 0;
int ans = 0;
int plen = strlen(p);
int slen = strlen(s);
while (j < slen) {
if (k == -1 || s[j] == p[k]) {
j++;
k++;
} else {
k = next[k];
}
if (k == plen) {
ans++;
k = next[k];
}
}
return ans;
}
int main() {
// freopen("in.txt","r",stdin);
int T;
char s[1000005];
char p[10005];//模式串
scanf("%d",&T);
while (T--) {
scanf("%s",p);
scanf("%s",s);
printf("%d\n",kmp(p,s));
}
return 0;
}