2020-06-06 09:25:49 +00:00
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;; Functions to calculate Fibonacci numbers
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2020-06-06 08:59:05 +00:00
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2020-06-06 09:25:49 +00:00
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;; Slow recursive version
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2020-06-06 08:59:05 +00:00
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(def slowFib (fn (n) (if (< n 2) n (+ (slowFib (- n 1)) (slowFib (- n 2))))))
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2020-06-06 09:25:49 +00:00
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;; Return the sum of the last 2 numbers in a sequence
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2020-10-17 07:15:14 +00:00
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(def sumOfLast (fn (l) (+ (last l) (penult l))))
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2020-06-06 08:59:05 +00:00
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2020-06-08 02:55:29 +00:00
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;; Faster version, return vector of n numbers, tail call optimized
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2020-06-06 08:59:05 +00:00
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(def fibListRec (fn (n l) (if (< (len l) n) (fibListRec n (push l (sumOfLast l))) l)))
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(def fibList (fn (n) (fibListRec n [0 1])))
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2020-10-17 07:15:14 +00:00
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(def fastFib (fn (n) (sumOfLast (fibList n))))
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2020-12-05 03:39:58 +00:00
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;; Add documentation
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(doc slowFib "Return the nth number from the Fibonacci sequence recursively.")
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(doc fastFib "Return the nth number from the Fibonacci sequence iteratively.")
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