Create HeapSort.java

Author: NayakNavin

Sorting Algorithms/HeapSort.java

@@ -0,0 +1,74 @@
+// Java program for implementation of Heap Sort 
+public class HeapSort 
+{ 
+	public void sort(int arr[]) 
+	{ 
+		int n = arr.length; 
+
+		// 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 
+			int temp = arr[0]; 
+			arr[0] = arr[i]; 
+			arr[i] = temp; 
+
+			// call max heapify on the reduced heap 
+			heapify(arr, i, 0); 
+		} 
+	} 
+
+	// 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) 
+	{ 
+		int largest = i; // Initialize largest as root 
+		int l = 2*i + 1; // left = 2*i + 1 
+		int r = 2*i + 2; // right = 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) 
+		{ 
+			int swap = arr[i]; 
+			arr[i] = arr[largest]; 
+			arr[largest] = swap; 
+
+			// Recursively heapify the affected sub-tree 
+			heapify(arr, n, largest); 
+		} 
+	} 
+
+	/* A utility function to print array of size n */
+	static void printArray(int arr[]) 
+	{ 
+		int n = arr.length; 
+		for (int i=0; i<n; ++i) 
+			System.out.print(arr[i]+" "); 
+		System.out.println(); 
+	} 
+
+	// Driver program 
+	public static void main(String args[]) 
+	{ 
+		int arr[] = {12, 11, 13, 5, 6, 7}; 
+		int n = arr.length; 
+
+		HeapSort ob = new HeapSort(); 
+		ob.sort(arr); 
+
+		System.out.println("Sorted array is"); 
+		printArray(arr); 
+	} 
+}