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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4.  
  5. ll coins(int x){ 
  6. 	if(x==0) return 3;
  7. 	return (ll)pow(3,x+1) + (ll)x * (ll)pow(3,x-1);
  8. }
  9.  
  10. int main() {
  11. 	// your code goes here
  12. 	int t=1;
  13. 	cin>>t;
  14. 	while(t--){
  15. 		ll n,k;
  16. 		cin>>n>>k;
  17. 		if(k >=n ){
  18. 			cout<<n*3<<"\n";
  19. 			continue;
  20. 		}
  21. 		if(n > n*k){
  22. 			cout<<-1<<'\n';
  23. 			continue;
  24. 		}
  25. 		ll ans = k*3ll;
  26.  
  27. 		ll two = (n-k)/2;
  28. 		ans += two*7;
  29. 		n = n - (k + two*2);
  30. 		if(n){
  31. 			if(two == (k-1)){
  32. 				cout<<-1<<'\n';
  33. 				continue;
  34. 			}
  35. 			ans += 4;
  36. 		}
  37. 		cout<<ans<<"\n";
  38.  
  39.  
  40.  
  41.  
  42. 	}
  43. 	return 0;
  44. }
Success #stdin #stdout 0s 5308KB
comments (?)
stdin
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8
1 1
3 3
8 3
2 4
10 10
20 14
3 2
9 1
stdout
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3
9
-1
6
30
63
10
31
https://ideone.com/BREm1Y
language:
C++ (gcc 8.3)
created:
15 days ago
visibility:
public

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