[LeetCode] 230. Kth Smallest Element in a BST

Given the root of a binary search tree, and an integer k, return the kth smallest value (1-indexed) of all the values of the nodes in the tree.

Example 1:

Input: root = [3,1,4,null,2], k = 1
Output: 1

Example 2:

Input: root = [5,3,6,2,4,null,null,1], k = 3
Output: 3

Constraints:

• The number of nodes in the tree is n.
• 1 <= k <= n <= 104
• 0 <= Node.val <= 104

Ans

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Solution

看到 BST 就知道老東西了

實際上這題就是考 Binary Tree Traversal 的方法概念

(Inorder, Preorder, Postorder)

因為是老東西了 我就不介紹了

如果有刷 LeetCode Easy 題目就知道

94. Binary Tree Inorder Traversal