Yes, during contest I preferred to write a ternary search besides the
geometry solution. Ironically, I couldn't fix the precision of the answer in
time =)
And I still don't see why binary search should work here... The distance
among time is neither in decreasing or increasing order.

2009/9/15 Carlos Guia <[email protected]>

> It can be solved with geometry, but I think writing ternary search is
> faster for many people(myself included) than doing the math on paper, also
> may be less error prone, it is easy to make a little mistake when doing math
> under pressure. And if I know 2 ways that will work, then I prefer the one
> that optimizes the solving speed. But for practice I think is better to try
> both, as having sharp math skills is very important anyway.
> Carlos Guía
>
>
>
> On Tue, Sep 15, 2009 at 9:41 AM, Andrea <[email protected]> wrote:
>
>>
>> On Sep 14, 6:52 pm, Renato Wolp <[email protected]> wrote:
>> > Should binary search work in this problem? I think it has to be a
>> ternary
>> > search...
>> >
>>
>> I think binary/ternary search is overkill. It is solvable using basic
>> geometry in O(1) for the minimum distance and time. Of course you need
>> first to get center of mass position and vector in O(N).
>>
>> You can find a (I hope) clear explanation of the geometric solution
>> method with the working python code here: http://e.nigma.be/archives/35
>>
>> --
>> Andrea
>>
>>
>
> >
>


-- 
Renato.

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