Create maximum-good-subarray-sum.py

Author: kamyu104

Python/maximum-good-subarray-sum.py

@@ -0,0 +1,22 @@
+# Time:  O(n)
+# Space: O(n)
+
+import collections
+
+
+# prefix sum
+class Solution(object):
+    def maximumSubarraySum(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: int
+        """
+        prefix = collections.defaultdict(lambda: float("inf"))
+        curr = 0
+        result = float("-inf")
+        for x in nums:
+            prefix[x] = min(prefix[x], curr)
+            curr += x
+            result = max(result, curr-prefix[x-k], curr-prefix[x+k])
+        return result if result != float("-inf") else 0