B - Oulipo HDU - 1686
题目链接:https://vjudge.net/contest/70325#problem/B
题目:
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.
InputThe 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.
OutputFor 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题意:给你两个字符串a,b,求出a在b中出现了多少次,用kmp即可
1 // 2 // Created by hanyu on 2019/8/13. 3 // 4 #include <algorithm> 5 #include <iostream> 6 #include <cstdio> 7 #include <cstring> 8 #include <queue> 9 #include <set> 10 #include<math.h> 11 #include<map> 12 using namespace std; 13 typedef long long ll; 14 const int maxn=1e6+10; 15 char str[maxn],str1[maxn]; 16 int nextt[maxn]; 17 void getnext() 18 { 19 memset(nextt,0,sizeof(nextt)); 20 int i=0,j=-1; 21 nextt[0]=-1; 22 int m=strlen(str1); 23 while(i<m) 24 { 25 if(j==-1||str1[i]==str1[j]) 26 { 27 ++i,++j; 28 if(str1[i]!=str1[j]) 29 nextt[i]=j; 30 else 31 nextt[i]=nextt[j]; 32 } else 33 j=nextt[j]; 34 } 35 } 36 int kmp() 37 { 38 int res=0; 39 int n=strlen(str); 40 int m=strlen(str1); 41 int i=0,j=0; 42 while(i<n){ 43 if(j==-1||str[i]==str1[j]) 44 i++,j++; 45 else 46 j=nextt[j]; 47 if(j==m) 48 { 49 j=nextt[j]; 50 res++; 51 } 52 } 53 return res; 54 } 55 int main() 56 { 57 int T; 58 scanf("%d",&T); 59 getchar(); 60 while(T--) 61 { 62 gets(str1); 63 gets(str); 64 getnext(); 65 printf("%d\n",kmp()); 66 } 67 return 0; 68 }
原文地址:https://www.cnblogs.com/Vampire6/p/11348947.html