N-ary Tree Postorder Traversal In PHP
Postorder traversal of n-ary tree: use stack to reverse recursion, push children first then parent node. Example: [5,6,3,2,4,1] for input [1,null,3,2,4,null,5,6]
590. N-ary Tree Postorder Traversa Difficulty: Easy Topics: Stack, Tree, Depth-First Search Given the root of an n-ary tree, return the postorder traversal of its nodes' values. Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples) Example 1: Input: root = [1,null,3,2,4,null,5,6] Output: [5,6,3,2,4,1] Example 2: Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14] Output: [2,6,14,11,7,3,12,8,4,13,9,10,5,1] Constraints: The number of the nodes in...