#249 Kth Smallest Integer in BST

Given the root of a binary search tree and an integer k, return the kth smallest value (1-indexed) in the tree.

A binary search tree satisfies the following constraints:

• Left subtree contains only values less than node's value
• Right subtree contains only values greater than node's value
• Both subtrees must also be valid BSTs

Constraints:

• 1 ≤ k ≤ Number of nodes in tree ≤ 1000
• 0 ≤ Node values ≤ 1000

Examples:

// Example 1:

//     2

//    / \

//   1   3

const root1 = createTree([2, 1, 3]);
console.log(kthSmallest(root1, 1));
// Output: 1


// Example 2:

//     4

//    / \

//   3   5

//  /

// 2

const root2 = createTree([4, 3, 5, 2]);
console.log(kthSmallest(root2, 4));
// Output: 5