Trees
A tree stores data in a hierarchy: one root node at the top, and every node can have children below it. A node with no children is a leaf. File folders, web pages (HTML) and company charts are all trees.
A binary tree allows at most two children per node, called left and right. Trees are naturally recursive: every child is itself the root of a smaller tree, so most tree code is a short recursive function. The height of a tree is the number of levels, which sets how long the longest path is.
What is a leaf in a tree?
Write leaves(node) that returns how many leaf nodes the tree has. Print leaves(root).
Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.
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