题目
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.
难度
Easy
方法
求出每个节点左右子树的深度，相加即为该节点对应的diameter，最后取最大的diameter即可
python代码
class TreeNode(object):
def __init__(self, x):
self.val = x
self.left = None
self.right = None
class Solution(object):
def diameterOfBinaryTree(self, root):
self.diameter = 0
def depth(node):
if node:
l_depth = depth(node.left)
r_depth = depth(node.right)
self.diameter = max(self.diameter, l_depth + r_depth)
return max(l_depth, r_depth) + 1
return 0
depth(root)
return self.diameter
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)
assert Solution().diameterOfBinaryTree(root) == 3
