[wvenable]

> Trees are the single most important data structure in computer science.

And yet I've never professionally had to reverse one or know if they are symmetrical.

[nostrademons]

I've had to recurse on a tree many, many times, though. Think of filesystems, DOM nodes, parse trees, control-flow graphs, nested annotations, tiered lookups, query builders, JSON structures, etc.

That's what this question is actually testing: can you decompose a problem statement, expressed in plain English, into subproblems and then solve the subproblems?

[eonw]

my thoughts exactly, never had to do that once.