Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 43547 Accepted: 17514

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

题意：求第一个字符串在第二个字符串出现的次数

kmp算法

最好先将字符串的长度求出来，此题有毒 ，一直超时，看了讨论区，说strlen()函数很耗时，然后改了，过了

代码如下：

#include<iostream>#include<stdio.h>#include<cmath>#include<string.h>#include<string>const int N=1000005;using namespace std;int next[N];void get_next(int next[],char s[],int len){    int i=0,j=-1;    j=next[0]=-1;    while(i<len)    {        if(j==-1||s[i]==s[j])        {            i++,j++;            next[i]=j;        }        else            j=next[j];    }}int kmp(char s[],char t[],int ls,int lt){    int i=0,j=0;    int ans=0;    while(i<ls)    {        if(j==-1 || s[i]==t[j])            i++,j++;        else            j=next[j];        if(j>=lt){            ans++;            j=next[j];//可以添加，优化        }    }    return ans;}int main(){    int n,ls,lt;    char s[N],t[N];    scanf("%d",&n);    while(n--)    {        memset(next,0,sizeof(next));        scanf("%s%s",s,t);        ls=strlen(s);        lt=strlen(t);        get_next(next,s,ls);        for(int i=0;i<ls;i++)            cout<<next[i]<<" ";        cout<<endl;        printf("%d\n",kmp(t,s,lt,ls));    }    return 0;}