二叉排序树 建树

TreeNode* Insert(TreeNode* root,int x) {
    if(root==NULL) {
        root=new TreeNode(x);
    }
    if(x<root->data) {
        root->leftchild=Insert(root->leftchild,x);
    } else if(x>root->data) {
        root->rightchild=Insert(root->rightchild,x);
    }
    return root;
}