Chat messages sit in an array sorted by id ascending. When the user taps a push notification to jump to a specific message, how would you write a function that returns that id plus up to 5 messages on each side, at most 11 in total, in ascending order?
Binary search finds the id's position (or its insertion point) in O(log n), then slice 5 on each side. The result is a subrange of the original array, so it's already ascending.
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