update

concepts/cpp/skip_list.md

@@ -10,10 +10,10 @@ within an ordered sequence of n elements.
 
 |            | Time complexity         |
 |------------|-------------------------|
-| Insertion  | O(log n)                |
-| Deletion   | O(log n)                |
-| Search     | O(log n)                |
-| Access     | O(n)                    |
+| Insertion  | $O(log n)$              |
+| Deletion   | $O(log n)$              |
+| Search     | $O(log n)$              |
+| Access     | $O(n)$                  |
 
 ## 💻 Implementation