99 Clojure Problems – 62: Collect the Internal Nodes of Binary Tree in a List

"An internal node of a binary tree has either one or two non-empty successors. Write a method internals to collect them in a list."

(deftest p62-internals
  (is (= '(a c) (internals '[a [b nil nil] [c [d nil nil] [e nil nil]]]))))

I used the same idea as in the two previous exercises: walk the tree and filter, just filtering for branch nodes this time. Again using a predicate I wrote earlier. Solution on Github.

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