HDU 1686 Oulipo / POJ 3461 Oulipo / SCU 2652 Oulipo （字符串匹配，KMP）

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

Http

HDU:https://vjudge.net/problem/HDU-1686 POJ:https://vjudge.net/problem/POJ-3461 SCU:https://vjudge.net/problem/SCU-2652

Source

字符串匹配，KMP

解决思路

直接运用KMP算法解题，请看我的这篇文章。

代码

#include<iostream> #include<cstdio> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; const int maxN=10001; const int maxM=1000001; const int inf=2147483647; int n,m; char W[maxN]; char T[maxM]; int F[maxN]; int main() { int TT; cin>>TT; for (int ti=1;ti<=TT;ti++) { scanf("%s",W); scanf("%s",T); n=strlen(W); m=strlen(T); F[0]=-1; for (int i=1;i<n;i++) { int j=F[i-1]; while ((W[j+1]!=W[i])&&(j!=-1)) j=F[j]; if (W[j+1]==W[i]) F[i]=j+1; else F[i]=-1; } int i=0,j=0; int Ans=0; while (i<m) { if (W[j]==T[i]) { i++; j++; if (j==n) { Ans++; j=F[j-1]+1; } } else if (j==0) i++; else j=F[j-1]+1; } cout<<Ans<<endl; } return 0; }

转载于:https://www.cnblogs.com/SYCstudio/p/7196103.html

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