g1301_1400.s1372_longest_zigzag_path_in_a_binary_tree

Class Solution

java.lang.Object

g1301_1400.s1372_longest_zigzag_path_in_a_binary_tree.Solution

public class Solution
extends Object

1372 - Longest ZigZag Path in a Binary Tree.

Medium

You are given the root of a binary tree.

A ZigZag path for a binary tree is defined as follow:

• Choose any node in the binary tree and a direction (right or left).
• If the current direction is right, move to the right child of the current node; otherwise, move to the left child.
• Change the direction from right to left or from left to right.
• Repeat the second and third steps until you can’t move in the tree.

Zigzag length is defined as the number of nodes visited - 1. (A single node has a length of 0).

Return the longest ZigZag path contained in that tree.

Example 1:

Input: root = [1,null,1,1,1,null,null,1,1,null,1,null,null,null,1,null,1]

Output: 3

Explanation: Longest ZigZag path in blue nodes (right -> left -> right).

Example 2:

Input: root = [1,1,1,null,1,null,null,1,1,null,1]

Output: 4

Explanation: Longest ZigZag path in blue nodes (left -> right -> left -> right).

Example 3:

Input: root = [1]

Output: 0

Constraints:

• The number of nodes in the tree is in the range [1, 5 * 104].
• 1 <= Node.val <= 100

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	longestZigZag(TreeNode root)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

longestZigZag

public int longestZigZag(TreeNode root)