kmp算法（POJ 3461 Oulipo）

http://www.cnblogs.com/dolphin0520/archive/2011/08/24/2151846.html

http://www.matrix67.com/blog/archives/115

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 22468 Accepted: 8962

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

130

bf算法RE=。=

#include<iostream>#include<string>using namespace std;int main(){int n,c;cin>>n;for(c=1;c<=n;c++){char s[100005],t[10005];cin>>t;cin>>s;int slen,tlen;tlen=strlen(t);slen=strlen(s);int i,j;int sum=0;for(i=0;i<slen;i++){j=0;while(t[j]==s[i]&&j<tlen){i++;j++;}if(j==tlen)sum=sum+1;            i=i-j+1;}cout<<sum<<endl;}    return 0;}

kmp算法求next[]数组~

#include<iostream>#include<string>using namespace std;int next[10005];char s[1000005],t[10005];void getnext(char *p,int *next){    int j=0,k=-1;     next[0]=-1;     while(!j || t[j]!='\0')     {         if(k==-1 || t[j]==t[k])         {             j++;             k++;             if(t[j]!=t[k])                 next[j]=k;             else                 next[j]=next[k];         }         else k=next[k];     }}int main(){int n,c;cin>>n;for(c=1;c<=n;c++){cin>>t>>s;int slen,tlen;slen=strlen(s);tlen=strlen(t);getnext(t,next);int i=0,j=0,sum=0;while(i<slen){if(j==-1||s[i]==t[j]){i++;j++;}else{j=next[j];       }if(j==tlen){sum=sum+1;j=next[j];}}cout<<sum<<endl;}return 0;}/*  3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN*/