> Being able to choose the appropriate data structure and explain trade-offs etc is much more valuable than simply knowing how to reverse a binary tree sorta st

> Being able to choose the appropriate data structure and explain trade-offs etc is much more valuable than simply knowing how to reverse a binary tree sorta stuff. Indeed. The simplest way to invert a binary tree is to include an "invert" flag in the data structure. If it's set, walk the tree right to left instead of left to right.