701. 二叉搜索树中的插入操作

struct TreeNode* insertIntoBST(struct TreeNode* root, int val) 
{
	if (root==NULL)
	{
		root = malloc(sizeof(struct TreeNode));
		root->val = val;
		root->left = root->right = NULL;
	}

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

	return root;
}