python_important_practice/InvertBinaryTree.py at main · dhirajpatra/python_important_practice · GitHub

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"""
Given the root of a binary tree, invert the tree, and return its root.


Example 1:


Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
Example 2:


Input: root = [2,1,3]
Output: [2,3,1]
Example 3:

Input: root = []
Output: []


Constraints:

The number of nodes in the tree is in the range [0, 100].
-100 <= Node.val <= 100
"""


# Definition for a binary tree node.
class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right


class Solution:
    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        # Base case: if the tree is empty, return None
        if not root:
            return None
        # Invert the left and right subtrees
        root.left, root.right = self.invertTree(root.right), self.invertTree(root.left)
        return root


# Example usage:
# Create a binary tree
tree = TreeNode(4)
tree.left = TreeNode(2)
tree.right = TreeNode(7)
tree.left.left = TreeNode(1)
tree.left.right = TreeNode(3)
tree.right.left = TreeNode(6)
tree.right.right = TreeNode(9)

solution = Solution()
inverted_tree = solution.invertTree(tree)

# You can now traverse and print the inverted tree to see the result.