Oulipo
Time Limit: 1000ms, Memory Limit: 65536K
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】
KMP模板题，都没有实现过KMP，这是第一次实现，主要就是getnext的实现，KMP复杂度O(n+m)，这题总复杂度O(T(n+m))
1 #include<stdio.h>
2 #include<string.h>
3 #include<iostream>
4 using namespace std;
5 int next[100010];
6 char s[1000010],p[10010];
7 int slen,plen;
8 void getnext() {
9 int i=0,j=-1;
10 next[0]=-1;
11 while(i<plen) {
12 if(j==-1||p[i]==p[j]) next[++i]=++j;
13 else j=next[j];
14 }
15 }
16 int kmpsearch() {
17 slen=strlen(s);plen=strlen(p);
18 int ans=0;
19 int i=0,j=0;
20 getnext();
21 while(i<slen&&j<plen) {
22 if (j==-1||s[i]==p[j]) ++i,++j;
23 else j=next[j];
24 if (j==plen) ans++,j=next[j];
25 }
26 return ans;
27 }
28 int main() {
29 int t;
30 scanf("%d",&t);
31 while(t--)
32 scanf("%s%s",p,s),printf("%d\n",kmpsearch());
33 return 0;
34 }
WA了好多次，谢谢ysy大聚聚