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) {
        if (root == nullptr) {
            return nullptr;
        } else if (root->val > val) {
            return searchBST(root->left, val);
        } else if (root->val < val) {
            return searchBST(root->right, val);
        } else {
            return root;
        }
    }
};