# https://leetcode.com/problems/diameter-of-binary-tree/
# 543. Diameter of Binary Tree
# Given a binary tree, you need to compute the length of the diameter of the tree.
# The diameter of a binary tree is the length of the longest path between any two nodes in a tree.
# This path may or may not pass through the root.
# Example:
# Given a binary tree
#           1
#          / \
#         2   3
#        / \
#       4   5
# Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].
# Note: The length of path between two nodes is represented by the number of edges between them.

# Recursive
def diameterOfBinaryTree(root):
    def getDepth(node):
        if not node:
            return 0
        return max(getDepth(node.left), getDepth(node.right)) + 1
    if not root:
        return 0
    d = getDepth(root.left) + getDepth(root.right)
    ld = diameterOfBinaryTree(root.left)
    rd = diameterOfBinaryTree(root.right)
    return max(d, ld, rd)
