lecode链接

    1. var searchBST = function(root, val) {
    2. if (root == null) return null;
    3. if (root.val === val) return root;
    4. if (root.val > val) {
    5. return searchBST(root.left, val);
    6. } else if (root.val < val) {
    7. return searchBST(root.right, val);
    8. }
    9. };