Leetcode 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.

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# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def diameterOfBinaryTree(self, root):
"""
:type root: TreeNode
:rtype: int
"""
self.result = 0
self.max_depth(root)
return self.result

def max_depth(self, root):
if not root:
return 0
left_depth = self.max_depth(root.left)
right_depth = self.max_depth(root.right)
self.result = max(self.result, (left_depth + right_depth))
return max(left_depth, right_depth) + 1

结果为42.84%，不错。