918 programming added

Author: prash5t

programming-py/918.py

@@ -0,0 +1,23 @@
+def maxCircularSubArray(nums):
+    """
+    using kadane approach
+    maximum circular sub array = max(maxiumNonCircularSubArray, SumOfWholeArray - mimimumNonCircularSubArray)
+    in case if all the elements of circular subarray is negative, max element of the list is the answer
+    """
+    max_so_far = min_so_far = max_here = min_here = nums[0]
+    negative_so_far = True
+    for num in nums[1:]:
+        if num >= 0:
+            negative_so_far = False
+        max_here, min_here = max(num, max_here+num), min(num, min_here + num)
+        max_so_far, min_so_far = max(
+            max_so_far, max_here), min(min_so_far, min_here)
+    if negative_so_far:
+        return max(nums)
+    return max(max_so_far, sum(nums)-min_so_far)
+
+
+# test below
+print(maxCircularSubArray([1, -2, 3, -2]))
+print(maxCircularSubArray([5, -3, 5]))
+print(maxCircularSubArray([-3, -2, -3]))