Description
Given the root of an n-ary tree, return the postorder traversal of its nodes values. Postorder visits all children first, then the root.
Examples
Input:
root = [1,null,3,2,4,null,5,6]Output:
[5,6,3,2,4,1]Explanation:
Postorder: children, then root.
Input:
root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10]Output:
[6,7,2,8,3,9,10,4,5,1]Explanation:
In postorder traversal, all children are visited before the parent. Node 2 has children [6,7], node 3 has child [8], and node 4 has children [9,10]. Order: 6,7 (children of 2), then 2, then 8 (child of 3), then 3, then 9,10 (children of 4), then 4, then 5 (leaf), and finally root 1.
Input:
root = []Output:
[]Explanation:
An empty tree has no nodes to traverse, so the postorder traversal returns an empty array. This represents the edge case where the tree is completely empty.
Constraints
- •
0 ≤ nodes ≤ 10⁴