Search in a Binary Search Tree.swift

// https://leetcode.com/problems/search-in-a-binary-search-tree/description/?envType=study-plan-v2&envId=leetcode-75

/*
You are given the root of a binary search tree (BST) and an integer val.

Find the node in the BST that the node's value equals val and return the subtree rooted with that node. If such a node does not exist, return null.
*/


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 searchBST(_ root: TreeNode?, _ val: Int) -> TreeNode? {
        guard let root = root else { return nil }

        if root.val == val {
            return root
        } else if root.val > val {
            return searchBST(root.left, val)
        } else {
            return searchBST(root.right, val)
        }
    }
}