Recursion on Binary Trees
Problem 68a - Extract a list of nodes of a tree in pre-order.
Problem 68b - Extract a list of nodes of a tree in in-order.
Problem 68c - Extract a list of nodesof a tree in post-order.
Problem 57 - Generate a binary tree from a list of integers.
Problem 61a - Count the leaves of a tree.
Problem 61b - Collect the leaves of tree into a list.
Problem 62a - Count the internal nodes of a tree.
Problem 62b - Collect the internal nodes of tree into a list.
Problem 63 - Construct a complete binary tree.
Problem 64 - Give coordinates to draw a binary tree
Problem 70 - Generate a dot-string representation of a tree.