二叉搜索树中的插入操作

class Solution {
public:
    TreeNode* insertIntoBST(TreeNode* root, int val) {
        if(root==NULL) root=new TreeNode(val);
        if(root->val<val){
            if(root->right==NULL) root->right=new TreeNode(val);
            else{
                insertIntoBST(root->right, val);
            }
        } 
        if(root->val>val){
           if(root->left==NULL) root->left=new TreeNode(val);
            else{
                insertIntoBST(root->left, val);
            }
        }
        return root;
    }
};