POJ_3461 Oulipo-KMP

题目链接:http://poj.org/problem?id=3461

简单明了KMP，不过需要统计出现的次数。

在每次查询到一个的时候依旧要沿着失配边走而不是直接回到开头。

代码:

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <vector>
#include <functional>
using namespace std;
#define inf 0x3f3f3f3f
#define maxn 2051



int getFail(char p[], int f[]){
    f[0] = f[1] = 0;
    int len = strlen(p);
    for(int i = 1; i < len; i++){
        int j  = f[i];
        while(j && p[i] != p[j]) j = f[j];
        f[i + 1] = (p[i] == p[j]? j + 1: 0);
    }
    return 0;
}
int KMP(char t[], char p[], int f[]){
    getFail(p, f);
    int tlen = strlen(t), plen = strlen(p);
    bool flag = false;
    int rec = 0;
    for(int i = 0, j = 0; i < tlen; i++){
        while(j && p[j] != t[i])
            j = f[j];
        if(p[j] == t[i])
            j++;
        if(j == plen){
            flag = true;
            rec++; j = f[j];
            continue;
        }
    }
    

    return rec;
}
char t[1000005], p[10005];
int f[10005];
int main(){
    int tp;
    scanf("%d", &tp);
    while(tp--){
        scanf("%s %s", p, t);
        memset(f, 0, sizeof(f));
        int res = KMP(t, p, f);
        printf("%d\n", res);
    }
}

题目:

Oulipo

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 40186		Accepted: 16146

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