700. Search in a Binary Search Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */

/*
Iterative Solution

Time Complexity: O(N) - If the tree is skewed it will visit all nodes.
Space Complexity: O(1)

N = Number of nodes in the binary search tree.
*/
class Solution {
    public TreeNode searchBST(TreeNode root, int val) {
//         if (root == null) {
//             return null;
//         }

        TreeNode cur = root;
        while (cur != null) {
            if (cur.val == val) {
                return cur;
            }
            cur = cur.val < val ? cur.right : cur.left;
        }
        return cur;
    }
}

/*
Recusrive Solution

Time Complexity: O(N) - If the tree is skewed it will visit all nodes.
Space Complexity: O(H)

N = Number of nodes in the binary search tree.
H = Height of tree. (Recursion Stack)
*/
class Solution {
    public TreeNode searchBST(TreeNode root, int val) {
        if (root == null) {
            return null;
        }
        if (root.val == val) {
            return root;
        }

        return val < root.val ? searchBST(root.left, val) : searchBST(root.right, val);
    }
}