Added code for "Maximum Subarray Sum"

MaxSubarraySum.cpp

@@ -0,0 +1,34 @@
+//Time Complexity : O(N)
+//Space Complexity : O(1)
+
+#include<bits/stdc++.h>
+using namespace std;
+
+int maxSubArraySum(int arr[], int size)
+{
+  int max_sum = INT_MIN, ending_index = 0;
+
+  for(int i=0; i<size; i++)
+  {
+    ending_index = ending_index + arr[i];
+    if(max_sum < ending_index)
+    {
+      max_sum = ending_index;
+    }
+    if(ending_index < 0)
+    {
+      ending_index = 0;
+    }
+  }
+  return max_sum;
+}
+
+int main()
+{
+  int arr[] = {4,-3,4,-1,-5,1,9,-6};
+  int n = sizeof(arr)/sizeof(arr[0]);
+
+  int ans = maxSubArraySum(arr,n);
+  cout << "Maximum Subarray Sum :" << ans;
+  return 0;
+}