230. Kth Smallest Element in a BST

Question

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.

Follow up:
What if the BST is modified (insert/delete operations) often and you need to find the kth smallest frequently? How would you optimize the kthSmallest routine?

Quick Hints

  • In order traversal

Solution

Time complexity

O (n)

Space complexity

O(log n)

Notes