LeetCode Solution, Medium, 230. Kth Smallest Element in a BST

230. Kth Smallest Element in a BST 題目敘述 Given the root of a binary search tree, and an integer k, return the k**th 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 Exampl...