Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 8708 | Accepted: 3419 |
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
基本KMP
源代码:
#include<iostream> #include<string.h> using namespace std; const int MAX=10005; int p[MAX]; //p[j]表示前j个字符都匹配,第j+1个不匹配时,j的最大前移 void PreKMP(char word[])//预处理 { int i,j; int len=strlen(word); p[1]=0; j=0; for(i=2;i<=len;i++) //注意:word[i]==word[p[i]] { while(j>0 && word[j]!=word[i-1]) j=p[j]; if(word[j]==word[i-1]) j++; p[i]=j; } } int KMP(char word[],char a[]) { int i,j,n,m,res=0; n=strlen(a); m=strlen(word); j=0; PreKMP(word); for(i=1;i<=n;i++) { while(j>0 && word[j]!=a[i-1]) j=p[j]; if(word[j]==a[i-1]) j++; if(j==m) { res ++; //出现加一次 j=p[j]; } } return res; } int main() { int t; char word[MAX]; char a[1000005]; cin>>t; while(t--) { scanf("%s%s",word,a); printf("%d\n",KMP(word,a)); } system("pause"); return 0; }