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
BAPC 2006 Qualification
题目大意：每次给你两个串 s1 s2，问s1在s2中出现了多少次。
KMP做……就当先存个板子吧。
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#include <iostream> #include <cstdio> #include <cstring> using namespace std; const int SZ = 1e6 + 10; int fail[SZ], cnt; char s1[SZ], s2[SZ]; void get_fail() { int len = strlen(s2 + 1); fail[1] = 0; for(int i = 2; i <= len; i++) { int p = fail[i - 1]; while(p && s1[i] != s2[p + 1]) p = fail[p]; if(s1[i] == s2[p + 1]) p++; fail[i] = p; } } void kmp() { int n = strlen(s1 + 1), m = strlen(s2 + 1); int p = 0; for(int i = 1; i <= n; i++) { while(p && s1[i] != s2[p + 1]) p = fail[p]; if(s1[i] == s2[p + 1]) p++; if(p == m) cnt++; } } int main() { int T; scanf("%d", &T); while(T--) { memset(fail, 0, sizeof(fail)); cnt = 0; scanf("%s", s2 + 1); scanf("%s", s1 + 1); get_fail(); kmp(); printf("%d\n", cnt); } return 0; } |