0701-insert-into-a-binary-search-tree.swift

/**
 * Question Link: https://leetcode.com/problems/insert-into-a-binary-search-tree/
 */

 /**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init() { self.val = 0; self.left = nil; self.right = nil; }
 *     public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
 *     public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
 *         self.val = val
 *         self.left = left
 *         self.right = right
 *     }
 * }
 */
class Solution {
    func insertIntoBST(_ root: TreeNode?, _ val: Int) -> TreeNode? {
        if root == nil {
            return TreeNode(val)
        }

        if root!.val > val {
            root?.left = insertIntoBST(root?.left, val)
        } else if root!.val < val {
            root?.right = insertIntoBST(root?.right, val)
        }
            
        return root
    }
}