hdoj 1686 Oulipo(KMP算法)

Oulipo

http://acm.hdu.edu.cn/showproblem.php?pid=1686

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 5903    Accepted Submission(s): 2370


Problem 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

华东区大学生程序设计邀请赛_热身赛

 

//高大上的KMP算法（数据结构P82-83  严蔚敏版）

#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
using namespace std;
char w[10005];
char t[1000005];
int nextval[10005];
void get_nextval(char s[])//求模式串S的nextval函数值并存入到nextval[]中
{
int i=0,j=-1;
nextval[0]=-1;
while(i<strlen(s))
{
if(j==-1||s[i]==s[j])
{
++i;
++j;
if(s[i]!=s[j])
nextval[i]=j;
else
nextval[i]=nextval[j];
}
else
j=nextval[j];
}
}
int KMP(char s[],char t[])//利用模式串t的nextval函数求t的主串s
{
int ls=strlen(s);
int lt=strlen(t);
int i=0,j=0,len=0;

while(i<=ls&&j<=lt)
{
if(j==-1||s[i]==t[j])//继续比较后继字符
{ ++i;++j; }
else
j=nextval[j]; // 模式串向右移动
if(j==lt)//通过nextval[]求得的j如果和模式串的长度相等就说明模式串在主串中出现了；
{
len++;
j=nextval[j];
}
}
return len;
}
int main()
{

int n;
scanf("%d",&n);
while(n--)
{
scanf("%s",w);
scanf("%s",t);
get_nextval(w);
int len=KMP(t,w);
printf("%d\n",len);
}
return 0;
}