Merge pull request #422 from aishalg/patch-2

Create Heap Sort in C++

Author: gantavyamalviya

CPP/sorting/Heap Sort in C++

@@ -0,0 +1,79 @@
+// C++ program for implementation of Heap Sort
+ 
+#include <iostream>
+using namespace std;
+ 
+// To heapify a subtree rooted with node i
+// which is an index in arr[].
+// n is size of heap
+void heapify(int arr[], int N, int i)
+{
+ 
+    // Initialize largest as root
+    int largest = i;
+ 
+    // left = 2*i + 1
+    int l = 2 * i + 1;
+ 
+    // right = 2*i + 2
+    int r = 2 * i + 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 != i) {
+        swap(arr[i], arr[largest]);
+ 
+        // Recursively heapify the affected
+        // sub-tree
+        heapify(arr, N, largest);
+    }
+}
+ 
+// Main function to do heap sort
+void heapSort(int arr[], int N)
+{
+ 
+    // Build heap (rearrange array)
+    for (int i = N / 2 - 1; i >= 0; i--)
+        heapify(arr, N, i);
+ 
+    // One by one extract an element
+    // from heap
+    for (int i = N - 1; i > 0; i--) {
+ 
+        // Move current root to end
+        swap(arr[0], arr[i]);
+ 
+        // call max heapify on the reduced heap
+        heapify(arr, i, 0);
+    }
+}
+ 
+// A utility function to print array of size n
+void printArray(int arr[], int N)
+{
+    for (int i = 0; i < N; ++i)
+        cout << arr[i] << " ";
+    cout << "\n";
+}
+ 
+// Driver's code
+int main()
+{
+    int arr[] = { 12, 11, 13, 5, 6, 7 };
+    int N = sizeof(arr) / sizeof(arr[0]);
+ 
+    // Function call
+    heapSort(arr, N);
+ 
+    cout << "Sorted array is \n";
+    printArray(arr, N);
+}