#95
To Tree, or not to Tree
| Difficulty: | Easy |
| Topics: | trees |
Write a predicate which checks whether or not
a given sequence represents a binary tree.
Each node in the tree must have a value,
a left child, and a right child.
 | (= (__ '(:a (:b nil nil) nil)) true) |
| (= (__ '(:a (:b nil nil))) false) |
| (= (__ [1 nil [2 [3 nil nil] [4 nil nil]]]) true) |
| (= (__ [1 [2 nil nil] [3 nil nil] [4 nil nil]]) false) |
| (= (__ [1 [2 [3 [4 nil nil] nil] nil] nil]) true) |
| (= (__ [1 [2 [3 [4 false nil] nil] nil] nil]) false) |
| (= (__ '(:a nil ())) false) |