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230.kth-smallest-element-in-a-bst.py
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230.kth-smallest-element-in-a-bst.py
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#
# @lc app=leetcode id=230 lang=python3
#
# [230] Kth Smallest Element in a BST
#
# @lc code=start
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def kthSmallest(self, root: Optional[TreeNode], k: int) -> int:
for _ in range(k - 1):
root = self.deleteNode(root, self.getSmallest(root))
return self.getSmallest(root)
def getSmallest(self, root: Optional[TreeNode]) -> int:
while (root.left):
root = root.left
return root.val
def deleteNode(self, root: Optional[TreeNode], key: int) -> Optional[TreeNode]:
if not root:
return None
if key < root.val:
root.left = self.deleteNode(root.left, key)
else:
if not root.right:
return None
root.val = self.getSmallest(root.right)
root.right = self.deleteNode(root.right, root.val)
return root
# @lc code=end