Descripción del Título:
给定一棵二叉搜索树,请找出其中第k大的节点。
示例 1:
输入: root = [3,1,4,null,2], k = 1
3
/ \
1 4
\
2
输出: 4
示例 2:
输入: root = [5,3,6,2,4,null,null,1], k = 3
5
/ \
3 6
/ \
2 4
/
1
输出: 4
# 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 kthLargest(self, root, k):
"""
:type root: TreeNode
:type k: int
:rtype: int
"""
## 注意搜索二叉树的性质
self.res,self.k=None,k
def dfs(node):
if not node:
return None
else:
dfs(node.right) #先遍历右节点
self.k -= 1
if self.k==0:
self.res=node.val #根节点
else:
dfs(node.left) #左节点
dfs(root)
return self.res