HeapSort implementation: 1st commit

Author: paulsagar1a

heap/HeapSort.java

@@ -0,0 +1,73 @@
+/*******************************************************
+ * @author SAGAR PAUL (paulsagar1a)
+ * @category heap
+ *******************************************************/
+
+//Heap sort algorithm
+
+package heap;
+
+public class HeapSort {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		int[] arr = {1, 11, 8, 5, 7, 10};
+		HeapSort obj = new HeapSort();
+		obj.sort(arr);
+		obj.printSortedArray(arr);
+	}
+
+	private void printSortedArray(int[] arr) {
+		// TODO Auto-generated method stub
+		int n = arr.length;
+        for (int i=0; i < n; ++i)
+            System.out.print(arr[i]+" ");
+        System.out.println();
+	}
+
+	private void sort(int[] arr) {
+		// TODO Auto-generated method stub
+		int n = arr.length;
+		
+		//build max heap
+		for(int i=n/2-1; i>=0; i--) {
+			heapify(arr, n, i);
+		}
+		
+		// Heap sort
+        for (int i=n-1; i>=0; i--)
+        {
+            int temp = arr[0];
+            arr[0] = arr[i];
+            arr[i] = temp;
+ 
+          	// Heapify root element
+            heapify(arr, i, 0);
+        }
+	}
+
+	private void heapify(int[] arr, int n, int i) {
+		// TODO Auto-generated method stub
+		//find largest among root, left child and right child
+		int largest = i;
+		int l = 2*i + 1;
+		int r = 2*i + 2;  
+		 
+        if (l < n && arr[l] > arr[largest])
+            largest = l;
+ 
+        if (r < n && arr[r] > arr[largest])
+            largest = r;
+ 
+      	// Swap and continue heapifying if root is not largest
+        if (largest != i)
+        {
+            int swap = arr[i];
+            arr[i] = arr[largest];
+            arr[largest] = swap;
+ 
+            heapify(arr, n, largest);
+        }
+	}
+
+}