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Oulipo(poj3461)(KMP)
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 25172 | Accepted: 10107 |
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
#include<stdio.h> #include<string.h> #include<algorithm> using namespace std; int next[10010],len1,len2; char a[1000010],s[10010]; void get_next(char *s) { int i=0,j=-1; next[0]=-1; while(i<len1) { if(j==-1||s[i]==s[j]) { i++; j++; next[i]=j; } else j=next[j]; } } int kmp(char *s,char *a) { get_next(s); int i=0,j=0,ans=0; while(i<len2) { if(j==-1||a[i]==s[j]) { i++; j++; } else { j=next[j]; } if(j==len1) { ans++; j=next[j]; } } return ans; } int main() { int test; scanf("%d",&test); while(test--) { scanf("%s%s",s,a); len1=strlen(s); len2=strlen(a); printf("%d\n",kmp(s,a)); } return 0; }
Oulipo(poj3461)(KMP)