Add solutions

Author: hypoxisaurea

contains-duplicate/hypoxisaurea.py

@@ -0,0 +1,13 @@
+from typing import List
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        num_set = set()
+
+        for num in nums:
+            if num in num_set:
+                return True
+            else:
+                num_set.add(num)
+
+        return False