feature: k radius subarray averages using sliding window prefix sum

arrays/KRadiusSubarrayAverages.py

@@ -0,0 +1,17 @@
+from typing import List
+
+
+# O(n) time || O(1) space
+def get_averages(self, nums: List[int], k: int) -> List[int]:
+    n = len(nums)
+    res = [-1] * n
+
+    left, curr_window_sum, diameter = 0, 0, 2 * k + 1
+    for right in range(n):
+        curr_window_sum += nums[right]
+        if right - left + 1 >= diameter:
+            res[left + k] = curr_window_sum // diameter
+            curr_window_sum -= nums[left]
+            left += 1
+
+    return res

arrays/test/test_get_averages.py

@@ -0,0 +1,15 @@
+import unittest
+
+from arrays.KRadiusSubarrayAverages import get_averages
+
+
+class MyTestCase(unittest.TestCase):
+    def test_get_averages(self):
+        self.assertEqual([-1, -1, -1, 5, 4, 4, -1, -1, -1], get_averages(self, [7, 4, 3, 9, 1, 8, 5, 2, 6], 3))
+
+    def test_get_averages_1(self):
+        self.assertEqual([100000], get_averages(self, [100000], 0))
+
+
+if __name__ == '__main__':
+    unittest.main()