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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int MAXN = 1e4 + 3;
  5. long long mu[MAXN];
  6.  
  7. bool is_prime[MAXN] = {false};
  8. void sieve_eratosthenes() {
  9. 	std::fill(&is_prime[0], &is_prime[0] + MAXN, true);
  10. 	is_prime[1] = false;
  11. 	for(int i = 2; i*i <= MAXN; i++){
  12. 		if(is_prime[i]){
  13. 			for(int j = i*i; j < MAXN; j += i){
  14. 				is_prime[j] = false;
  15. 			}
  16. 		}
  17. 	}
  18. }
  19. void compute_mu() {
  20.     mu[1] = 1;
  21.     for(int i = 2; i < MAXN; i++) {
  22.         if(is_prime[i]) {
  23.             mu[i] = -1;
  24.             for(int j = MAXN/i; j > 1; j--) {
  25.                 if(j == i || j*i >= MAXN) continue;
  26.                 mu[j*i] = mu[j] * (-1);
  27.             }
  28.         }
  29.     }
  30. }
  31.  
  32. long long F[MAXN];
  33.  
  34. int main() {
  35.     ios_base::sync_with_stdio(false);
  36.     long long alpha, beta;
  37.     alpha = 1234123;
  38.     beta = 34123;
  39.     sieve_eratosthenes();
  40.     compute_mu();
  41.     for(int g = 1; g < MAXN; g++) {
  42.         for(int k = g; k < MAXN; k += g) {
  43.             F[g] += mu[k/g] * (alpha/k) * (beta/k);
  44.         }
  45.     }
  46.     for(int g = 1; g < MAXN; g++) {
  47.         long long temp = (alpha/g) * (beta/g);
  48.         for(int k = g*2; k < MAXN; k += g) {
  49.             temp -= F[k];
  50.         }
  51.         assert(temp == F[g]);
  52.     }
  53.     return 0;
  54. }
  55.  
Success #stdin #stdout 0s 3628KB
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https://ideone.com/5BmeNy
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

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