added a cpp file for kadane algorithm

data_structures/Arrays/CPP/kadaneAlgo.cpp

@@ -0,0 +1,31 @@
+        // kadane's algo
+
+#include<iostream>
+
+using namespace std;
+
+int maximum_subarray_sum(int arr[] , int n){
+
+    int cs = 0;
+    int largest =0;
+
+    for(int i=0; i<n ; i++){
+        cs = cs + arr[i];
+
+        if(cs < 0){
+            cs = 0;
+        }
+
+        largest = max(largest , cs);
+    }
+
+    return largest;
+}
+
+int main()
+{
+    int arr[] = { -2,3 ,4 -1 , 5, -12 , 6,1,3};
+    int n = sizeof(arr)/sizeof(int);
+    cout<< "The maximum sum is "<<maximum_subarray_sum(arr , n) <<endl;
+
+}