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| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 36128 | Accepted: 14584 |
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
/* * POJ 3461 Oulipo * 求模式串在文本串中出现的次数 * * KMP套版题，可看前一篇转载的博客，对KMP讲的很详细 */ #include <stdio.h> #include <string.h> #include <iostream> using namespace std; const int MAXN = 1000000+10; const int MAXM = 10000+10; void Get_Next(char* P,int* next) { int i=0,k=-1; int plen=strlen(P); next[0]=-1; while(i<plen) { if(k==-1||P[k]==P[i]) { next[++i]=++k; } else k=next[k]; } } int KMP_count(char* T,char* P,int* next) { int ans=0; int i=0,j=0; int tlen=strlen(T); int plen=strlen(P); while(i<tlen) { //如果j=-1，或者当前字符匹配成功(即S[i] == P[j],继续往后匹配 if(j==-1||T[i]==P[j]) { i++,j++; } else { //失配了，根据next数组往后移动 j=next[j]; } //如果此时P的匹配长度等于了原有长度，说明出现了一次，答案加1 //并且跳回前一步继续进行匹配 if(j==plen) { ans++; j=next[j]; } } return ans; } char W[MAXM],T[MAXN]; int nxt[MAXM]; int main() { int t; scanf("%d",&t); while(t--) { scanf("%s%s",W,T); Get_Next(W,nxt); printf("%d\n",KMP_count(T,W,nxt)); } return 0; }
POJ 3461 Oulipo (求模式串在文本串中出现的次数)
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原文地址：http://www.cnblogs.com/wangdongkai/p/5797159.html
