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- (20 pts) Write the same
mergesortfunction as described in exercise 26.1.2, except decompose the problem "top-down" rather than "bottom-up". You will need to define a functionsplit: (list-of number) -> 2-element-structure-of-lists-of-number)that partitions its input into two lists of approximately (+/- 1) the same length in O(n) time where n is the length of the input list.(split l)returns a 2-element structure containing two lists of numbers. See below for hints in defining a 2-element structure. After splitting the list in half,mergesortrecursively sorts each half and then merges them together. Be careful about attempting to split a one-element list!
Hints for writing the "split" function:
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