| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 26857 | Accepted: 10709 |
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
1 #include<cstdio>
2 #include<cstring>
3 char t[10000 + 10] , s[1000000 + 10] ;
4 int nxt [10000 + 10] ;
5 int T ;
6 int lens , lent ;
7
8 void PMT ()
9 {
10 nxt [0] = -1 ;
11 for (int i = 1 , j = -1 ; i < lent ; i++) {
12 while (j != -1 && t[i] != t[j + 1] ) {
13 j = nxt[j] ;
14 }
15 nxt[i] = t[i] == t[j + 1] ? ++ j : j ;
16 }
17 }
18
19 void kmp ()
20 {
21 int ret = 0 ;
22 PMT () ;//partial match table
23 for (int i = 0 , j = - 1 ; i < lens ; i++) {
24 while (j != - 1 && s[i] != t[j + 1] ) {
25 j = nxt [j] ;
26 }
27 if (s[i] == t[j + 1]) {
28 j ++ ;
29 if (j == lent - 1) {
30 j = nxt [j] ;
31 ret ++ ;
32 }
33 }
34 }
35 printf ("%d\n" , ret );
36 }
37
38 int main ()
39 {
40 // freopen ("a.txt" , "r" , stdin ) ;
41 scanf ("%d" , &T) ;
42 getchar () ;
43 while (T--) {
44 memset (nxt , 0 , sizeof(nxt) ) ;
45 gets (t) ;
46 gets (s) ;
47 lens = strlen (s) ;
48 lent = strlen (t) ;
49 // puts (t) , puts (s) ;
50 kmp () ;
51 }
52 return 0 ;
53 }
来源：https://www.cnblogs.com/get-an-AC-everyday/p/4381975.html