Binary Tree Reverse Level Order Traversal- LeetCode

Problem Statement Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (i.e, from left to right, level by level from leaf to root). For example:Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its bottom-up level order traversal as: [ [15,7], [9,20], [3] ] Intuition Alternative Explanation Binary