25August2024 - 145. Binary Tree Postorder Traversal.py

#145. Binary Tree Postorder Traversal

# 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 postorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
        if not root:
            return []
        return self.postorderTraversal(root.left) + self.postorderTraversal(root.right) + [root.val]
# Time complexity: O(n)