POJ 3461 Oulipo

来源：互联网发布：德勤monitor知乎编辑：程序博客网时间：2024/05/17 01:04

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 38364 Accepted: 15439

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

Source

BAPC 2006 Qualification

HASH 版本：

 1 #include<cstdio> 2 #include<cstring> 3 using namespace std; 4 #define P 29 5 const int N=1e6+10; 6 char s1[N],s2[N]; 7 int p,ans,S,n1,n2,ha[N]; 8 void get_P(){ 9     p=1;10     for(int i=1;i<=n2;i++)p*=P;11 } 12 void get_Hash(){13     ha[0]=0;S=0;14     for(int i=1;i<=n2;i++) S=S*P+s2[i]-'a';15     for(int i=1;i<=n1;i++) ha[i]=ha[i-1]*P+s1[i]-'a';16 }17 int query(int l,int r){18     return ha[r]-ha[l-1]*p;19 }20 int main(){21     int T;scanf("%d",&T);22     while(T--){23         ans=0;24         scanf("%s%s",s2+1,s1+1);25         n1=strlen(s1+1);n2=strlen(s2+1);26         get_P();get_Hash();27         for(int i=n2,x;i<=n1;i++){28             x=query(i-n2+1,i);29             if(x==S) ans++;30         }31         printf("%d\n",ans);32     }33     return 0;34 }

KMP版本：

 1 #include<cstdio> 2 #include<cstring> 3 using namespace std; 4 const int N=1e6+10; 5 char s[N],t[N]; 6 int T,n,m,next[N],ans; 7 void Get_Next(){ 8     int j=0; 9     for(int i=2;i<=m;i++){10         while(j && t[i] != t[j+1])j=next[j];11         if(t[i] == t[j+1])j++;12         next[i]=j;13     }14 }15 void KMP(){16     int j=0;17     for(int i=1;i<=n;i++){18         while(j && s[i] != t[j+1])j=next[j];19         if(s[i]==t[j+1])j++;20         if(j==m)ans++,j=next[j];21     }22 }23 int main()24 {25     scanf("%d",&T);26     while(T--){27         scanf("%s%s",t+1,s+1);28         ans=0;29         n=strlen(s+1),m=strlen(t+1);30         Get_Next();31         KMP();32         printf("%d\n",ans);33     }34     return 0;35 }

0 0