POJ_3461 Oulipo-KMP

Posted 2020-09-17 EricJeffrey

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:

 1 #include <cstdio>
 2 #include <cstdlib>
 3 #include <cmath>
 4 #include <cstring>
 5 #include <algorithm>
 6 #include <string>
 7 #include <queue>
 8 #include <stack>
 9 #include <map>
10 #include <set>
11 #include <vector>
12 #include <functional>
13 using namespace std;
14 #define inf 0x3f3f3f3f
15 #define maxn 2051
16 
17 
18 
19 int getFail(char p[], int f[]){
20     f[0] = f[1] = 0;
21     int len = strlen(p);
22     for(int i = 1; i < len; i++){
23         int j  = f[i];
24         while(j && p[i] != p[j]) j = f[j];
25         f[i + 1] = (p[i] == p[j]? j + 1: 0);
26     }
27     return 0;
28 }
29 int KMP(char t[], char p[], int f[]){
30     getFail(p, f);
31     int tlen = strlen(t), plen = strlen(p);
32     bool flag = false;
33     int rec = 0;
34     for(int i = 0, j = 0; i < tlen; i++){
35         while(j && p[j] != t[i])
36             j = f[j];
37         if(p[j] == t[i])
38             j++;
39         if(j == plen){
40             flag = true;
41             rec++; j = f[j];
42             continue;
43         }
44     }
45     
46 
47     return rec;
48 }
49 char t[1000005], p[10005];
50 int f[10005];
51 int main(){
52     int tp;
53     scanf("%d", &tp);
54     while(tp--){
55         scanf("%s %s", p, t);
56         memset(f, 0, sizeof(f));
57         int res = KMP(t, p, f);
58         printf("%d\n", res);
59     }
60 }

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