Build the PrimitiveEasy
Invert Binary Tree
Write `invert_tree(root)` swapping every left and right child, and returning the root.
The code is four lines. What the interviewer is listening for is whether you can name what you are doing — this is a post-order or pre-order traversal, and unusually the order does not affect the result. Say that rather than typing in silence.
What to expect: A timer starts when you begin. Edit the starter code, run it against the test suite as many times as you like, then finish when you're done. The reference solution and interviewer follow-up questions unlock only after you finish.