Given the root
of a binary tree, collect a tree's nodes as if you were doing this:
 Collect all the leaf nodes.
 Remove all the leaf nodes.
 Repeat until the tree is empty.
Example 1:
1
/ \ 1
2 3 => / => 1
/ \ 2
4 5
Input: root = [1,2,3,4,5]
Output: [[4,5,3],[2],[1]]
Explanation:
[[3,5,4],[2],[1]] and [[3,4,5],[2],[1]] are also considered correct answers
since per each level it does not matter the order on which elements are returned.
Example 2:
Input: root = [1]
Output: [[1]]
Constraints:
 The number of nodes in the tree is in the range
[1, 100]
. 100 <= Node.val <= 100

