Binary Tree Postorder Traversal 🦚

Question

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

Example 1:

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

Example 2:

Input: root = []
Output: []

Example 3:

Input: root = [1]
Output: [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?

Solution

Time Complexity O(n)

Space Complexity O(h) where h is the max height of the tree

Time Complexity O(n)

Space Complexity O(h) where h is the max height of the tree

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