# Beautiful Code, Chapter 3.
# Produces the expected runtime of Quicksort, for every integer from 1 to N.

runtime: (N) ->
  [sum, t]: [0, 0]
  for n in [1..N]
    sum += 2 * t
    t: n - 1 + sum / n
  t

print(runtime(3) is 2.6666666666666665)
print(runtime(5) is 7.4)
print(runtime(8) is 16.92142857142857)