Kth Smallest in Binary Search Tree

Problem Statement

Given the root of a binary search tree (BST) and an integer

, return the smallest element in the BST.

Rules and Constraints

• The BST is not necessarily balanced.
• The number of nodes in the BST will be in the range
  [1, 10^4]
  .
• The values of the nodes will be in the range
  [1, 10^5]
  .
• The input BST is guaranteed to be a valid binary search tree.
• You must return the
  kth
  smallest element.

Note: The solution should be efficient in terms of time complexity, as the input values are relatively large.

Example

Input: {"root":[3,1,4,null,2],"k":1} Output: 1