标签：not help code class you fun ini self solution
Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.
Note:
You may assume k is always valid, 1 ≤ k ≤ BST‘s total elements.
Example 1:
Input: root = [3,1,4,null,2], k = 1 3 / 1 4 2 Output: 1
Example 2:
Input: root = [5,3,6,2,4,null,null,1], k = 3
5
/ 3 6
/ 2 4
/
1
Output: 3
Follow up:
What if the BST is modified (insert/delete operations) often and you need to find the kth smallest frequently? How would you optimize the kthSmallest routine?
# 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 kthSmallest(self, root, k): """ :type root: TreeNode :type k: int :rtype: int """ self.k = k self.res = None self.helper(root) return self.res def helper(self, root): if root is None: return None self.helper(root.left) self.k -= 1 if self.k == 0: self.res = root.val return self.helper(root.right)
230. Kth Smallest Element in a BST
标签：not help code class you fun ini self solution
原文地址：https://www.cnblogs.com/boluo007/p/12466888.html
