Add files via upload

Author: RUPAKparajuli07

Day137Question137/Solution.py

@@ -0,0 +1,11 @@
+from typing import List
+
+class Solution:
+    def singleNumber(self, nums: List[int]) -> int:
+        ones, twos = 0, 0
+        
+        for num in nums:
+            ones = (ones ^ num) & ~twos
+            twos = (twos ^ num) & ~ones
+        
+        return ones