LeetCode #145: Binary Tree Postorder Traversal
β’ 113 words β’ 1 min β’ updated
LeetCode #145: Binary Tree Postorder Traversal:
Sequence:
- left
- right
- current node
Recursive #
python
# 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 root is None:
return []
return self.postorderTraversal(root.left) + self.postorderTraversal(root.right) + [root.val]Alternative:
python
# 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]:
ans = []
def postorder(node):
if node:
postorder(node.left)
postorder(node.right)
ans.append(node.val)
postorder(root)
return ans