Binary Tree Zigzag Level Order Traversal
Question
Given the root of a binary tree, return the zigzag level order traversal of its nodes’ values. (i.e., from left to right, then right to left for the next level and alternate between).
Example 1
Input:
root = [3,9,20,null,null,15,7]Output:[[3],[20,9],[15,7]]
Example 2
Input:
root = [1]Output:[[1]]
Example 3
Input:
root = []Output:[]
Constraints
The number of nodes in the tree is in the range
[0, 2000].
-100 <= Node.val <= 100
Hints
No hints available.