struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode() : val(0), left(nullptr), right(nullptr) {}
    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    TreeNode(int x, TreeNode* left, TreeNode* right) : val(x), left(left), right(right) {}
};

class Solution {
public:
    TreeNode* searchBST(TreeNode* root, int val) {
        while (root != nullptr && root->val != val) {
            if (val < root->val) {
                root = root->left;
            }
            else {
                root = root->right;
            }
        }
        return root;
    }
};