alt Hacker NewsI feel the same way about inverting a binary tree, but a lot of people act like it's an arduous request. I am guessing it's because they've never read the description of what inverting a binary tree is, but maybe people are just that bad at recursion.
You can go your entire career without recursing, or using a tree data structure in its raw form (i.e. you only use it as part of a library)