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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. const int MAXN = 1e6 + 10;
  6.  
  7. int n, a[MAXN];
  8. int cnt[MAXN], s[MAXN], used[MAXN];
  9. vector <int> v[MAXN];
  10.  
  11. int main() {
  12. 	for (int i = 2; i < MAXN; ++i) {
  13. 		if(s[i] == 0) {
  14. 			for (int j = i; j < MAXN; j += i) {
  15. 				s[j] += i;
  16. 			}
  17. 		}
  18. 	}
  19. 	for (int j = 2; j < MAXN; ++j) {
  20. 		for (int i = 2 * j; i < MAXN; i += j) {
  21. 			if(s[i] % s[j] == 0) {
  22. 				v[i].push_back(j);
  23. 			}
  24. 		}
  25. 	}
  26. 	int t;
  27. 	scanf("%d", &t);
  28. 	while (t--) {
  29. 		scanf("%d", &n);
  30. 		for (int i = 1; i <= n; ++i) {
  31. 			scanf("%d", &a[i]);
  32. 			cnt[a[i]]++;
  33. 		}
  34. 		long long ans = 0;
  35. 		for (int i = 1; i <= n; i++) {
  36. 			if(!used[a[i]]) {
  37. 				ans += 1ll * cnt[a[i]] * (cnt[a[i]] - 1);
  38. 				for (auto j : v[a[i]]) {
  39. 					ans += 1ll * cnt[a[i]] * cnt[j];
  40. 				}
  41. 				used[a[i]]=1;
  42. 			}
  43. 		}
  44. 		for(int i = 1; i <= n; i++) {
  45. 			used[a[i]] = 0;
  46. 			cnt[a[i]] = 0;
  47. 		}
  48. 		printf("%lld\n", ans);
  49. 	}
  50. }
Success #stdin #stdout 0.3s 52628KB
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https://ideone.com/b1dJXm
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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