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POJ3461 Oulipo[KMP]
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 36916 | Accepted: 14904 |
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
Source
KMP裸题 出现几次
//// main.cpp// poj3461//// Created by Candy on 10/19/16.// Copyright © 2016 Candy. All rights reserved.//#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N=1e6+5,M=1e4+5;int T,f[M];// already i(0...i-1),now pos ichar s[N],p[M];void getFail(){ size_t m=strlen(p); f[0]=f[1]=0; for(int i=1;i<m;i++){ int j=f[i]; while(j&&p[i]!=p[j]) j=f[j]; f[i+1]=p[i]==p[j]?j+1:0; }}int kmp(){ getFail(); int cnt=0; size_t n=strlen(s),m=strlen(p); int j=0; for(int i=0;i<n;i++){ while(j&&s[i]!=p[j]) j=f[j]; if(s[i]==p[j]) j++; if(j==m) cnt++; } return cnt;}int main(int argc, const char * argv[]) { scanf("%d",&T); while(T--){ scanf("%s%s",p,s); printf("%d\n",kmp()); } return 0;}
POJ3461 Oulipo[KMP]