Add problem 53 - Maximum Subarray

Author: anirudhology

problems/dynamic_programming/maximum_subarray.py

@@ -0,0 +1,11 @@
+from typing import List
+
+
+class MaximumSubarray:
+    @staticmethod
+    def maxSubArray(nums: List[int]) -> int:
+        local_maxima, global_maxima = nums[0], nums[0]
+        for i in range(1, len(nums)):
+            local_maxima = max(local_maxima + nums[i], nums[i])
+            global_maxima = max(local_maxima, global_maxima)
+        return global_maxima

tests/dynamic_programming/maximum_subarray_test.py

@@ -0,0 +1,24 @@
+import unittest
+
+from problems.dynamic_programming.maximum_subarray import MaximumSubarray
+
+
+class TestMaximumSubarray(unittest.TestCase):
+    def setUp(self):
+        self.maximum_subarray = MaximumSubarray()
+
+    def test_max_sub_array_single_element(self):
+        self.assertEqual(self.maximum_subarray.maxSubArray([5]), 5)
+
+    def test_max_sub_array_all_negative(self):
+        self.assertEqual(self.maximum_subarray.maxSubArray([-1, -2, -3, -4]), -1)
+
+    def test_max_sub_array_mixed(self):
+        self.assertEqual(self.maximum_subarray.maxSubArray([-2, 1, -3, 4, -1, 2, 1, -5, 4]), 6)
+
+    def test_max_sub_array_all_positive(self):
+        self.assertEqual(self.maximum_subarray.maxSubArray([1, 2, 3, 4, 5]), 15)
+
+
+if __name__ == '__main__':
+    unittest.main()