Description
A ZigZag path alternates between going left and right child. Given the root, return the length of the longest ZigZag path.
Examples
Input:
root = [1,null,1,1,1,null,null,1,1,null,1,null,null,null,1,null,1]Output:
3Explanation:
Zigzag of length 3.
Input:
root = [1,1,1,null,1,null,1,1,null,null,null,null,1]Output:
4Explanation:
The longest zigzag path starts from the root, goes left to node 1, then right to node 1, then left to node 1, then right to node 1. This creates a zigzag pattern of length 4: root → left → right → left → right.
Input:
root = [1]Output:
0Explanation:
A single node tree has no edges to traverse, so the longest zigzag path has length 0. There are no left or right moves possible from the root.
Constraints
- •
1 ≤ nodes ≤ 5 × 10⁴