JAVA算法练习题day35

44.二叉搜索树中第K小的元素

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):def kthSmallest(self, root, k):""":type root: Optional[TreeNode]:type k: int:rtype: int"""#中序遍历结果是升序，输出idx为K-1就可以nums = []def dfs(root):if root is None:returndfs(root.left)nums.append(root.val)dfs(root.right)dfs(root)return nums[k-1]