poj 3461 Oulipo,裸kmp

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Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 32373		Accepted: 13093

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

BAPC 2006 Qualification

 

 

15266997

njczy2010

3461

Accepted

1736K

125MS

G++

1147B

2016-03-14 17:00:52

 

题意：

裸的kmp

 

代码：

#include <iostream>
#include <cstdio>
#include <map>
#include <cstring>
#include <algorithm>

using namespace std;

#define N 1000005
#define ll long long

int TT;
char s[N];
char t[N];
int next[N];
int ans;
int l;
int lt;

void get_next()
{
    int i,j;
    i = 0;
    j = -1;
    next[0] = -1;
    while(i<l)
    {
        if(j == -1 || s[i] == s[j]){
            i++;j++;next[i] = j;
        }
        else{
            j = next[j];
        }
    }
}

void kmp()
{
    int i,j;
    i = 0;
    j = 0;
    while(i < lt)
    {
        if(j == -1 || t[i] == s[j]){
            if(j == l - 1){
                ans ++;
                j = next[j];
            }
            else{
                i++;j++;
            }
        }
        else{
            j = next[j];
        }
    }
}

int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    scanf("%d",&TT);
    while(TT--){
    //while(scanf("%I64d%I64d",&n,&k)!=EOF){
        ans = 0;
        scanf("%s",s);
        l = strlen(s);
        scanf("%s",t);
        lt = strlen(t);
        get_next();
        kmp();
        printf("%d\n",ans);
    }
    return 0;
}