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| 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:
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 }
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原文地址：http://www.cnblogs.com/get-an-AC-everyday/p/4381975.html
