二叉搜索树的最近公共祖先(简单难度)

class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
         if(root == null) {
            return null;
        }
        if(p == root || q == root) {
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left,p,q);
        TreeNode right = lowestCommonAncestor(root.right,p,q);
        if(left == null) {
           return right;
        }
        if(right == null) {
            return left;
        }
        if(left != null && right != null) {
            return root;
        }
        return null;
    }
}