How painful it wrong questions
Subject to the effect
Given n-$ $ and $ x $, when seeking a uniform ring on randomly generated spans no more than all the points when the points $ n-$ $ \ frac {2π} {x} $ (i.e., there is a size $ probability \ frac {2π} {x} $ arcs can cover all points)
Topic analysis
Consider the final case where the starting point must be a clockwise, the other $ n-1 $ point must be after its $ \ frac {1} {x} $ on the arc, i.e., $ {\ frac {1} { x}} ^ {n-1} $.
The added points are in order, so each point may be used as a starting point. Answer at $ n \ times {\ frac {1} {x}} ^ {n-1} $
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