Added code for Heap sort

Java/heapsort.java

@@ -0,0 +1,80 @@
+import java.util.*;
+class Heap_Sort
+{
+    void printArray(int arr[],int n)
+    {
+        //int n = arr.length;
+        for (int i=0; i<n; ++i)
+            System.out.print(arr[i]+" ");
+        System.out.println();
+    }
+    public static void main(String args[])
+    {
+        Scanner sc  = new Scanner(System.in);
+        Heap_Sort hs = new Heap_Sort();
+        int arr[] = new int[1000000];
+        int T = sc.nextInt();
+        while(T>0)
+        {
+            int n = sc.nextInt();
+            for(int i=0;i<n;i++)
+                arr[i] = sc.nextInt();
+
+            Solution ob=new Solution();
+            ob.heapSort(arr,n);
+            hs.printArray(arr,n);
+            T--;
+        }
+    }
+
+}
+
+
+// } Driver Code Ends
+
+
+
+class Solution
+{
+    //Function to build a Heap from array.
+    void buildHeap(int arr[], int n)
+    {
+        // Your code here
+        for(int i=(n-2)/2;i>=0;i--)
+            heapify(arr,n,i);
+    }
+
+    //Heapify function to maintain heap property.
+    void heapify(int arr[], int n, int i)
+    {
+        // Your code here
+        int l=2*i+1;
+        int r=2*i+2;
+        int largest=i;
+
+        if(l<n && arr[l]>arr[largest]) largest=l;
+        if(r<n && arr[r]>arr[largest]) largest=r;
+
+        if(i!=largest){
+            int temp=arr[i];
+            arr[i]=arr[largest];
+            arr[largest]=temp;
+            heapify(arr,n,largest);
+        }
+     }
+
+    //Function to sort an array using Heap Sort.
+    public void heapSort(int arr[], int n)
+    {
+        //code here
+        buildHeap(arr,n);
+        for(int i=n-1;i>=0;i--){
+            //swap first last
+            int temp=arr[i];
+            arr[i]=arr[0];
+            arr[0]=temp; 
+            heapify(arr,i,0);
+        }
+    }
+ }
+