poj3461

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 7493 Accepted: 2925

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

简单的kmp算法

只是最终记录的不是第一个匹配的字串的下标，而是能够最多匹配的淄川的个数，值得注意的是在匹配完成的时候，j==m，需要添加一行代码

j=next[m];否则会造成下次循环式b[j]的下表越界，虽然可以ac但是严谨还是好点的，

代码如下

#include<cstdio>#include<cstring>#include <iostream>#include <cstdlib>using namespace std;const int maxn=1000020,maxn1=10050;char a[maxn],b[maxn];int next[maxn],n,m;void next_d(){    next[0]=0;    next[1]=0;    int j;    for(int i=1;i<m;i++)    {   j=next[i];        while(j&&b[j]!=b[i])            j=next[j];        if(b[i]==b[j])            next[i+1]=j+1;        else            next[i+1]=0;    }}int kmp(){    int i,j=0,count=0;    for(i=0;i<n;i++)    {        while(j&&a[i]!=b[j])            j=next[j];        if(a[i]==b[j])            j++;        if(j==m)        {             j=next[m];//注意！！！防止下标越界             count++;        }    }    return count;}int main(){    int g;    scanf("%d",&g);    while(g--)    {        scanf("%s",b);        scanf("%s",a);        n=(int)strlen(a);        m=(int)strlen(b);        next_d();        int result=kmp();        printf("%d\n",result);    }    return 0;}