Oulipo

Time limit

1000 ms

Memory limit

32768 kB

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

题意：给出一个模式串，一个原串。让找原串中有多少个模式串。用正常的BF，O=WT算法会超时。新学了KMP算法。

#include<bits/stdc++.h>const int maxn=1e6+10;using namespace std;int Next[maxn];char str[maxn],mo[maxn];void getNext(){    int i=0;    int j=-1;    int len=strlen(mo);    while(i<len)    {        if(j==-1||mo[i]==mo[j])        {            i++;            j++;            Next[i]=j;        }        else            j=Next[j];    }}int kmp(){    int i=0;    int j=0;    int ans=0;    int l1=strlen(str);    int l2=strlen(mo);    while(i<l1)    {        if(j==-1||mo[j]==str[i])        {            i++;            j++;        }        else j=Next[j];        if(j==l2) ans++;    }    return ans;}int main(){    int t;    scanf("%d",&t);    while(t--)    {        scanf("%s%s",mo,str);        Next[0]=-1;        getNext();        printf("%d\n",kmp());    }}