Description of the Problem

Given the root of a binary tree, return the postorder traversal of its nodes' values.

Example 1:

1 - 2 - 3

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

Example 2:

Input: root = []
Output: []

Example 3:

Input: root = [1]
Output: [1]

Example 4:

2 - 1

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

Example 5:

1 - 2

Input: root = [1,null,2]
Output: [2,1]

Constraints:

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

Follow up:

Recursive solution is trivial, could you do it iteratively?

Code

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution(object): def postorderTraversal(self, root): """ :type root: TreeNode :rtype: List[int] """ 

Link To The LeetCode Problem

LeetCode