< Back 226. Invert Binary Tree We invert a binary tree. Pretty straightforward, just recursively swap the nodes. The solution is as follows: class Solution: def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]: if not root: return root root.left, root.right = self.invertTree(root.right), self.invertTree(root.left) return root _ Time Complexity: O(n) - Where n is the number of nodes in the tree. _ Space Complexity: O(h) - Where h is the height of the tree.