Create heapsort.cpp

heapsort.cpp

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+// 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);
+}