docs(docs): add 271 Encode/Decode Strings and 98 Validate BST pages

apps/docs/content/(array)/217-contains-duplicate.mdx

@@ -42,7 +42,14 @@ flowchart TD
 
 ## Solution
 
-```js
+<CodeGroup>
+
+```py Python
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+```
+
+```js JavaScript
 /**
  * @param {number[]} nums
  * @return {boolean}
@@ -59,6 +66,8 @@ var containsDuplicate = function(nums) {
 };
 ```
 
+</CodeGroup>
+
 ## Explanation
 
 <YouTube id="3OamzN90kPg" title="Contains Duplicate - Leetcode 217 - Python" />