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威尔逊定理 HDU2973 YAPTCHA

2024-10-22 03:28:39   209人阅读

YAPTCHA

Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 930    Accepted Submission(s): 491


Problem Description
The math department has been having problems lately. Due to immense amount of unsolicited automated programs which were crawling across their pages, they decided to put Yet-Another-Public-Turing-Test-to-Tell-Computers-and-Humans-Apart on their webpages. In short, to get access to their scientific papers, one have to prove yourself eligible and worthy, i.e. solve a mathematic riddle.


However, the test turned out difficult for some math PhD students and even for some professors. Therefore, the math department wants to write a helper program which solves this task (it is not irrational, as they are going to make money on selling the program).

The task that is presented to anyone visiting the start page of the math department is as follows: given a natural n, compute
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where [x] denotes the largest integer not greater than x.
 

 

Input
The first line contains the number of queries t (t <= 10^6). Each query consist of one natural number n (1 <= n <= 10^6).
 

 

Output
For each n given in the input output the value of Sn.
 

 

Sample Input
13 1 2 3 4 5 6 7 8 9 10 100 1000 10000
 

 

Sample Output
0 1 1 2 2 2 2 3 3 4 28 207 1609
 

 

Source
Central European Programming Contest 2008

 

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 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cmath>
 6 using namespace std;
 7 int t;
 8 bool check[3000010];
 9 int num[1000010];
10 void Eratosthenes(){
11     check[0]=1;
12     check[1]=1;
13     for(int i=2;i<=sqrt(3000010);i++)
14         if(!check[i])
15             for(int j=2*i;j<=3000010;j+=i) check[j]=1;
16 }
17 int main(){
18     scanf("%d",&t);
19     Eratosthenes();
20     for(int i=1;i<=1000000;i++)
21         if(check[3*i+7]) num[i]=num[i-1];
22         else num[i]=num[i-1]+1;
23     int a;
24     for(int i=1;i<=t;i++){
25         scanf("%d",&a);
26         printf("%d\n",num[a]);
27     }
28     return 0;
29 }

 

 

威尔逊定理 HDU2973 YAPTCHA


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