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
找到二叉搜索树的第k小的值。
二叉搜索树的很多题都可以用中序遍历来解决,因为二叉搜索树的中序遍历是按照从小到大排序的。
class Solution:
def kthSmallest(self, root: TreeNode, k: int) -> int:
final=[]
def inorder(root):
if not root:return root
inorder(root.left)
final.append(root.val)
inorder(root.right)
inorder(root)
return final[k-1]