Create maximum_subarray_sum.py

Author: Amogh Singhal

maximum_subarray_sum.py

@@ -0,0 +1,25 @@
+# Problem: Given a list of positive and negative numbers, find the maximum subarray sum.
+# Constraint: Solve it in O(n)
+
+# Solution: Use two variables to hold sums
+# a. overall sum -- initialize to first element
+# b. partial sum -- initialize to first element
+# Traverse over the whole array
+# If the current element is greater than partial sum, swap the partial sum with the current element
+# If the partial sum is greater than overall sum, swap overall with partial sum
+# the overall sum will be the contiguous subarray with the largest sum
+
+def maxSubArraySum(arr):
+  max_so_far = arr[0]
+  current_max = arr[0]
+
+  for i in range(1,len(arr)):
+    current_max = max(arr[i], current_max + arr[i])
+    max_so_far = max(max_so_far, current_max)
+  
+  return max_so_far
+
+sampleArr = [-2, -3, 4, -1, -2, 1, 5, -3]
+
+solution = maxSubArraySum(sampleArr)
+print(solution)