# 230. Kth Smallest Element in a BST

## Medium

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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_.

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**Example 1:**

![](https://assets.leetcode.com/uploads/2021/01/28/kthtree1.jpg)

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

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/01/28/kthtree2.jpg)

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

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**Constraints:**

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

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**Follow up:** If the BST is modified often (i.e., we can do insert and delete operations) and you need to find the kth smallest frequently, how would you optimize?
