feat(189-rotate-array): add py3 solution

0189_rotate-array/python3/extra_space.py

@@ -0,0 +1,16 @@
+# Time: O(N)
+# Space: O(N)
+class Solution:
+    def rotate(self, nums: List[int], k: int) -> None:
+        """
+        Do not return anything, modify nums in-place instead.
+        """
+        n = len(nums)
+        result = [None] * n
+        
+        for i, num in enumerate(nums):
+            new_i = (i + k) % n
+            result[new_i] = num
+            
+        for i, num in enumerate(nums):
+            nums[i] = result[i]