POJ 3461 Oulipo【KMP，子串出现次数，可重叠】

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 36896 Accepted: 14896

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

Source

BAPC 2006 Qualification

原题链接：http://poj.org/problem?id=3461

题意：输入两个字符串，问第一个字符串在第二个字符串中的出现次数。（可重叠）。

直接套模板：

AC代码：

#include <cstdio>#include <cstring>#include <iostream>using namespace std;const int maxn=100000+5;char p[maxn];char s[maxn*100];int lenp,lens;int Next[maxn];void getNext(){    int i=0,j=-1;    memset(Next,0,sizeof(Next));    Next[0]=-1;    while(i<lenp)    {        if(j==-1||p[i]==p[j])        {            i++,j++;            Next[i]=j;        }        else            j=Next[j];    }}int KMP(){    int i=0,j=0;    int ans=0;    while(i<lens)    {        if(j==-1||s[i]==p[j])        {            i++,j++;        }        else            j=Next[j];        if(j==lenp)        {            ans++;            j=Next[j];            //若两个不同的匹配没有交集则j=0,            //若存在交集则j=next[j];        }    }    return ans;}int main(){    int T;    cin>>T;    while(T--)    {        cin>>p>>s;        lens=strlen(s);        lenp=strlen(p);        getNext();        cout<<KMP()<<endl;    }    return 0;}

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