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.
LeetCode:链接
给定一棵二叉树,计算任意两节点之间的边数的最大值。
这道题目可以通过求二叉树深度的方法来求,在dfs中返回的是二叉树的深度,但是dfs的过程中更新当前的最长的路径,一个结点所经过的路径的长度,等于它左子树的深度+右子树的深度(二叉树的深度其实就是root和最低的结点之间,连接线的个数)。
# 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.ans = 0
def getdepth(root):
if not root:
return 0
left = getdepth(root.left)
right = getdepth(root.right)
self.ans = max(self.ans, left + right)
return max(left, right) + 1
getdepth(root)
return self.ans