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Kth Smallest Element in a BST

Given the level-order array of a BST and an integer k, return the kth smallest value (1-indexed) in the BST.

Input:

3,1,4,null,2
1

Output:

Reasoning:

The given level-order array 3,1,4,null,2 represents a Binary Search Tree (BST) where the parent node is 3, the left child is 1, the right child is 4, and the right child of the left child is 2.
The BST is traversed in-order to obtain the sorted array: 1, 2, 3, 4.
Since k is 1, we need to find the $1^{st}$ smallest element in the sorted array.
The $1^{st}$ smallest element is 1, which is the final output.

Editor

Python 3.13.1

0/0

Run code to see test results.

📘

MediumTrees

Given the level-order array of a BST and an integer k, return the kth smallest value (1-indexed) in the BST.

Input:

3,1,4,null,2
1

Output:

Reasoning:

The given level-order array 3,1,4,null,2 represents a Binary Search Tree (BST) where the parent node is 3, the left child is 1, the right child is 4, and the right child of the left child is 2.
The BST is traversed in-order to obtain the sorted array: 1, 2, 3, 4.
Since k is 1, we need to find the $1^{st}$ smallest element in the sorted array.
The $1^{st}$ smallest element is 1, which is the final output.

Editor

Python 3.13.1

0/0

Run code to see test results.