Binary Tree Zigzag Level Order Traversal
MediumP2Coding
Given the root of a binary tree, return its level-order traversal in zigzag order: the first level left to right, the second right to left, the third left to right again, and so on. Return one inner array per level; an empty tree gives [].
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
- 0 <= number of nodes <= 2000
- -100 <= Node.val <= 100
Hints
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Saved automatically
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