Added solution for Maximum Sum Subarray

Author: Codenegaar

AlgorithmsDesignExamples.pro

@@ -4,4 +4,5 @@ SUBDIRS += \
     InsertionSort \
     SelectionSort \
     MergeSort \
-    BinarySearch
+    BinarySearch \
+    MaximumSubarray

MaximumSubarray/MaximumSubarray.pro

@@ -0,0 +1,7 @@
+TEMPLATE = app
+CONFIG += console c++11
+CONFIG -= app_bundle
+CONFIG -= qt
+
+SOURCES += \
+        main.cpp

MaximumSubarray/main.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+using namespace std;
+
+int maximumSubarray(int* arr, int start, int end);
+void printArray(int* arr, int n);
+
+int main()
+{
+    int arr[9] = {-4, 5, -2, -2, 6, -4, 3, -4, 4};
+    printArray(arr, 9);
+    int max = maximumSubarray(arr, 0, 8);
+    cout << "Max sum subarray: " << max << endl;
+    return 0;
+}
+
+int maximumSubarray(int *arr, int start, int end)
+{
+    if (start == end)
+        return arr[start];
+
+    int mid = (start + end) / 2;
+    int l = maximumSubarray(arr, start, mid);
+    int r = maximumSubarray(arr, mid + 1, end);
+
+    int maxLeft;
+    int temp = 0;
+    bool flag = true;   //checks if maxLeft is initialized
+
+    for (int i = mid; i >= start; i--)
+    {
+        temp += arr[i];
+        if (flag || temp > maxLeft)
+            maxLeft = temp;
+        flag = false;
+    }
+
+    temp = 0;
+    flag = true;
+    int maxRight;
+    for (int i = mid + 1; i <= end; i++)
+    {
+        temp += arr[i];
+        if (flag || temp > maxRight)
+            maxRight = temp;
+        flag = false;
+    }
+
+    if (l >= r && l >= (maxLeft + maxRight))
+        return l;
+    if (r >= l && r >= (maxLeft + maxRight))
+        return r;
+    return maxLeft + maxRight;
+}
+
+void printArray(int *arr, int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        if (i)
+            cout << ", ";
+        cout << arr[i];
+    }
+    cout << endl;
+}