POJ 3461 Oulipo（KMP模板题）

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 43141 Accepted: 17358

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

3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN

Sample Output

130

AC代码：

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn = 1e4+10;const int max2 = 1e6+10;char W[maxn];char T[max2];int next[maxn];void get_next(int len){int k = 0;next[0] = 0;for(int p = 1; p < len; p++){while(k > 0 && T[p]!=T[k]){k = next[k-1];}if(T[k] == T[p])k++;next[p] = k;}}int main(){int n ;scanf("%d",&n);while(n--){scanf("%s%s",W,T);int len1 = strlen(W);int len2 = strlen(T);get_next(len1);int cnt = 0;int k = 0, j = 0;while(k<len1 && j<len2){if(W[k] == T[j]){if(k == len1-1){k = next[k];j++;cnt++;}    else k++,j++;}else if(k == 0) j++;else k = next[k-1];}printf("%d\n",cnt);}return 0;}