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" />

apps/docs/content/(array)/271-encode-and-decode-strings.mdx

@@ -0,0 +1,48 @@
+---
+title: '271. Encode and Decode Strings'
+description: Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings
+sidebar:
+  label: 'Encode and Decode Strings'
+  badge: 'Medium'
+---
+
+<Badge variant="accent">Array</Badge>
+
+::::warning
+Could you write a generalized algorithm to work on any possible set of characters?
+::::
+
+### Example 1:
+- Input: `dummy_input = ["Hello","World"]`
+- Output: `["Hello","World"]`
+- Explanation: Machine `1`: Codec encoder = new Codec(); String msg = encoder.encode(strs); Machine `1` ---msg---> Machine `2` Machine `2`: Codec decoder = new Codec(); `String[] strs` = decoder.decode(msg);
+
+### Example 2:
+- Input: `dummy_input = [""]`
+- Output: `[""]`
+
+### Constraints:
+
+- `1 <= strs.length <= 200`
+- `0 <= strs[i].length <= 200`
+- `strs[i]` contains any possible characters out of 256 valid ASCII characters.
+
+## Solution
+
+```py
+class Codec:
+    def encode(self, strs: List[str]) -> str:
+        """Encodes a list of strings to a single string.
+        """
+        
+
+    def decode(self, s: str) -> List[str]:
+        """Decodes a single string to a list of strings.
+        """
+        
+
+
+# Your Codec object will be instantiated and called as such:
+# codec = Codec()
+# codec.decode(codec.encode(strs))
+```