The Mirror Flip

A easy Python interview practice problem on DataDriven. Write and execute real python code with instant grading.

Domain

Python

Difficulty

easy

Seniority

L3

Problem

A binary tree arrives as nested dicts, where each node is `{"val": int, "left": node or null, "right": node or null}` and a missing child is `null`. Return its mirror image: at every node the left and right children are swapped, all the way down to the leaves. A `null` root returns `null`.

Summary

Sometimes the fastest fix is to swap everything.

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