KthSmallestElementInBST

Published at 2022-05-06

# 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:
        res = []
        def dfs(node):
            if not node: return
            dfs(node.left)
            res.append(node.val)
            dfs(node.right)
        
        dfs(root)
        return res[k-1]
    
    """
    중위순회(inorder)랑 아주아주 비슷. 중위순회 응용문제임
    """