Oulipo
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 23667 | Accepted: 9492 |
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
题解: 统计W串在T串中出现的次数。根据数据规模，KMP算法可AC。
代码：
1 #include<stdio.h>
2 #include<string.h>
3 #include<math.h>
4 #include<ctype.h>
5 #include<stdlib.h>
6 #include<stdbool.h>
7
8 #define rep(i,a,b) for(i=(a);i<=(b);i++)
9 #define clr(x,y) memset(x,y,sizeof(x))
10 #define sqr(x) (x*x)
11 #define LL long long
12
13 int i,j,n,num,
14 f[1000003];
15
16 char p[10003],t[1000003];
17
18 int init()
19 {
20 clr(p,‘\0‘);
21 clr(t,‘\0‘);
22 clr(f,0);
23 num=0;
24
25 scanf("%s",p);
26 scanf("%s",t);
27
28 return 0;
29 }
30
31 void kmp(char *t, char *p, int *f)
32 {
33 int n,m,j;
34 n = strlen(t); m = strlen(p);
35 getFail(p,f);
36
37 j = 0;
38
39 for(i = 0;i < n;i++) {
40 while(j && p[j] != t[i]) j=f[j];
41 if(p[j] == t[i]) j++;
42 if(j == m) num++;
43 }
44
45
46 }
47
48 void getFail(char p[],int f[])
49 {
50 int m,j,i;
51 m = strlen(p);
52 f[0] = 0;f[1] = 0;
53
54 for(i = 1;i < m;i++) {
55 j = f[i];
56 while(j && p[i] != p[j]) j = f[j];
57 f[i+1]=p[i]==p[j] ? j+1 : 0;
58 }
59 }
60
61 int main()
62 {
63 int T;
64 scanf("%d",&T);
65
66 while(T--) {
67 init();
68 getFail(p,f);
69 kmp(t,p,f);
70 printf("%d\n",num);
71 }
72 return 0;
73 }
[POJ] 3461 Oulipo [KMP算法]