A story with skeletons
A one-kilometer long corridor has two exits, both of which are big fireplaces.
Some skeletons located in this corridor walk at a speed of one meter per second. Once a skeleton reaches one of the exits, he is instantaneously consumed. If two skeletons hit one eachother, they bounce and walk immediately in the opposite direction.
Q1: Can the skeletons stay in the corridor for an infinite time?
Q2: Knowing that two skeletons cannot be in the same initial position, how can one place 64 skeletons (position, direction) in a way such that the last skeleton stays in the corridor as long as possible?
(Thanks to T.K.)
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