Merge pull request #240 from mendoza/maximum-circular-subarray-sum

Maximum circular subarray sum

Author: amritansh22

Diff for: MaximumCircularSubarraySum.cpp

@@ -0,0 +1,40 @@
+#include <iostream>
+
+/*
+    Simple Kadane's algorithm to
+    find maximum subarray sum
+*/
+
+int kadane(int a[], int n) {
+  int highest = 0, ending = 0;
+  for (int i = 0; i < n; i++) {
+    ending = ending + a[i];
+    if (ending < 0) ending = 0;
+    if (highest < ending) highest = ending;
+  }
+  return highest;
+}
+
+/*
+    Function returns maximum
+    circular contiguous sum in a[]
+*/
+
+int maxCircularSum(int a[], int n) {
+  int max = kadane(a, n);
+  int wrap = 0;
+  for (int i = 0; i < n; i++) {
+    wrap += a[i];
+    a[i] = -a[i];
+  }
+  wrap = wrap + kadane(a, n);
+  return (wrap > max) ? wrap : max;
+}
+
+int main() {
+  int a[] = {11, 10, -20, 5, -3, -5, 8, -13, 10};
+  int n = sizeof(a) / sizeof(a[0]);
+  std::cout << "Maximum circular subarray sum: " << maxCircularSum(a, n)
+            << std::endl;
+  return 0;
+}