| 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
1 #include <iostream>
2 #include <cstdio>
3 #include <map>
4 #include <cstring>
5 #include <algorithm>
6
7 using namespace std;
8
9 #define N 1000005
10 #define ll long long
11
12 int TT;
13 char s[N];
14 char t[N];
15 int next[N];
16 int ans;
17 int l;
18 int lt;
19
20 void get_next()
21 {
22 int i,j;
23 i = 0;
24 j = -1;
25 next[0] = -1;
26 while(i<l)
27 {
28 if(j == -1 || s[i] == s[j]){
29 i++;j++;next[i] = j;
30 }
31 else{
32 j = next[j];
33 }
34 }
35 }
36
37 void kmp()
38 {
39 int i,j;
40 i = 0;
41 j = 0;
42 while(i < lt)
43 {
44 if(j == -1 || t[i] == s[j]){
45 if(j == l - 1){
46 ans ++;
47 j = next[j];
48 }
49 else{
50 i++;j++;
51 }
52 }
53 else{
54 j = next[j];
55 }
56 }
57 }
58
59 int main()
60 {
61 //freopen("in.txt","r",stdin);
62 //freopen("out.txt","w",stdout);
63 scanf("%d",&TT);
64 while(TT--){
65 //while(scanf("%I64d%I64d",&n,&k)!=EOF){
66 ans = 0;
67 scanf("%s",s);
68 l = strlen(s);
69 scanf("%s",t);
70 lt = strlen(t);
71 get_next();
72 kmp();
73 printf("%d\n",ans);
74 }
75 return 0;
76 }
来源：https://www.cnblogs.com/njczy2010/p/5276356.html