Pattern 22: LeetCode Interview Patterns24 sections · 736 units
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LeetCode 226 Invert Binary Tree - Solution

The core idea

Recursively swap the left and right children of every node.

For each node:

  1. Recursively invert the left subtree.
  2. Recursively invert the right subtree.
  3. Swap the left and right children.

The base case: if the node is null, return null.

You can also do this iteratively using BFS or DFS with a stack, visiting each node and swapping its children.