[kuangbin带你飞]专题十六 KMP & 扩展KMP & Manacher B - Oulipo HDU - 1686(kmp)

缺乏、安全感 2021-10-29 08:04 276阅读 0赞

# B - Oulipo HDU - 1686 #

题目链接：[https://vjudge.net/contest/70325\#problem/B][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 }

转载于:https://www.cnblogs.com/Vampire6/p/11348947.html

[https_vjudge.net_contest_70325_problem_B]: https://vjudge.net/contest/70325#problem/B