heap sort using cpp

06. Sorting/Heap sort using cpp

@@ -0,0 +1,77 @@
+#include <iostream>
+using namespace std;
+
+// function to heapify the tree
+void heapify(int arr[], int n, int root)
+{
+int largest = root; // root is the largest element
+int l = 2*root + 1; // left = 2*root + 1
+int r = 2*root + 2; // right = 2*root + 2
+
+   // If left child is larger than root
+if (l < n && arr[l] > arr[largest])
+largest = l;
+
+   // If right child is larger than largest so far
+if (r < n && arr[r] > arr[largest])
+largest = r;
+
+   // If largest is not root
+if (largest != root)
+   {
+      //swap root and largest
+swap(arr[root], arr[largest]);
+
+      // Recursively heapify the sub-tree
+heapify(arr, n, largest);
+   }
+}
+
+// implementing heap sort
+void heapSort(int arr[], int n)
+{
+   // build heap
+for (int i = n / 2 - 1; i >= 0; i--)
+heapify(arr, n, i);
+
+   // extracting elements from heap one by one
+for (int i=n-1; i>=0; i--)
+   {
+      // Move current root to end
+swap(arr[0], arr[i]);
+
+      // again call max heapify on the reduced heap
+heapify(arr, i, 0);
+   }
+}
+
+/* print contents of array - utility function */
+void displayArray(int arr[], int n)
+{
+   for (int i=0; i<n; ++i)
+   cout << arr[i] << " ";
+   cout << "\n";
+}
+
+// main program
+int main()
+{
+int heap_arr[] = {4,17,3,12,9};
+int n = sizeof(heap_arr)/sizeof(heap_arr[0]);
+cout<<"Input array"<<endl;
+displayArray(heap_arr,n);
+
+heapSort(heap_arr, n);
+
+cout << "Sorted array"<<endl;
+displayArray(heap_arr, n);
+}
+Output:
+
+Input array
+
+4    17     3    12   9
+
+Sorted array
+
+3    4     9     12    17