poj3461——Oulipo（KMP）

Oulipo

Time Limit: 1000MS Memory Limit: 65536K

Total Submissions: 15416Accepted: 6179

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
Source

BAPC 2006 Qualification

解析：KMP模板题，刚学了kmp，找一道裸题刷哈！！！

#include<cstdio>#include<algorithm>#include<cstdlib>#include<cstring>#include<iostream>using namespace std;int next[10010];int lens,lent;char S[1000010],T[1000010];void get_next(){    int i=0;int j=-1;next[i]=j;    while(i<lent)    {        if(j==-1 || T[i]==T[j])        {            ++i;++j;            next[i]=j;        }else j=next[j];    }}void kmp(){    int i=0;int j=0; int ans=0;    while (i<lens && j<lent)    {        if(j==-1 || S[i]==T[j]){i++;j++;}else j=next[j];        if(j>=lent)        {            //printf("%d\n",i-lent);注释部分是输出第一次匹配的位置，也可以输出每次匹配的位置            ans++;            j=next[j];        }    }    printf("%d\n",ans);}int main(){freopen("kmp.in","r",stdin);freopen("kmp.out","w",stdout);int test;cin>>test;    for(int i=1;i<=test;i++){   scanf("%s\n",T);   scanf("%s\n",S);   lens=strlen(S);lent=strlen(T);   get_next();kmp();    }    return 0;}