python code added

Author: GouravRusiya30

.project

@@ -0,0 +1,11 @@
+class Solution:
+def singleNumber(self, nums: List[int]) -> int:
+    d = dict()
+    for i in range(len(nums)) : 
+        if nums[i] not in d : 
+            d[nums[i]] = 1
+        else:
+            d[nums[i]] += 1
+    for key, value in d.items() : 
+        if value == 1 : 
+            return key