### Spheniscine's blog

By Spheniscine, history, 2 months ago,

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### F – GCD or MIN

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• +35

 » 2 months ago, # |   0 Spheniscine For problem F -> how is the rough bound O(M^(1/3)) ? I don't understand the maximum bound of D can someone explain ?
•  » » 2 months ago, # ^ |   +1 It's just a rough "rule of thumb", the exact values can be found on this page.The divisor function is hard to describe usefully in terms of big $O$, but it can be proven to always be $< 3.528 M ^ {1/3}$, which can be considered $O(M ^ {1/3})$In theoretical terms it's actually $O(M^\varepsilon)$ for all $\varepsilon > 0$, but it converges really slowly.
•  » » » 2 months ago, # ^ |   0 Thanks for the explanation
 » 2 months ago, # |   0 Spheniscine can you explain why this submission has failed for problem D https://atcoder.jp/contests/abc191/submissions/20025093I followed the editorial but it is still failing on test cases handmade_marginal_00.txt
•  » » 2 months ago, # ^ | ← Rev. 2 →   0 I don't have a C++ debugger handy but might I ask why you have +1 and -1 in these lines:  LL high = Y + 1; LL low = Y - 1; 
•  » » » 2 months ago, # ^ |   0 It might be redundant but I think I added it to be on the safer side
•  » » » » 2 months ago, # ^ | ← Rev. 2 →   0 I don't know if it's safer or might be causing the issue. Note that the partial result for some rows can actually be zero, if the circle crosses the line but doesn't actually include any lattice points.
•  » » » » » 2 months ago, # ^ |   0 Spheniscinewell I tried this and it worked but I don't understand why it was failing earlierhttps://atcoder.jp/contests/abc191/submissions/20025313