chore: clean up obsolete examples

apps/docs/content/hash-table/217-contains-duplicate.mdx

@@ -42,32 +42,12 @@ flowchart TD
 
 ## Solution
 
-<CodeGroup>
-
-```py Python
+```py
 class Solution:
     def containsDuplicate(self, nums: List[int]) -> bool:
+        return len(set(nums)) != len(nums)
 ```
 
-```js JavaScript
-/**
- * @param {number[]} nums
- * @return {boolean}
- */
-var containsDuplicate = function(nums) {
-  const freq = {};
-  for (let n of nums) {
-    freq[n] = (freq[n] || 0) + 1;
-    if (freq[n] >= 2) {
-      return true;
-    }
-  } 
-  return false;
-};
-```
-
-</CodeGroup>
-
 ## Explanation
 
 <YouTube id="3OamzN90kPg" title="Contains Duplicate - Leetcode 217 - Python" />