69.a) Write a function to convert a tree to a string where empty subtrees are represented by a dot. For example, the tree shown in problem P67 is represented as 'abd..e..c.fg...'.

69.b) Construct a tree from a dot notation string.

# # # THIS IS A STUB # # #

Example in Elm:

import Html exposing (text)
import List

f : Int -> Int
-- your implementation goes here

main = text (toString (f 0))

Result:

4

Solutions