Merge pull request #239 from tpriyanshu90/master

heap sort in java

Author: probot-auto-merge[bot]

Sorting Algorithm/Heap Sort/Java/HeapSort.class

@@ -0,0 +1,73 @@
+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); 
+    } 
+}