Merge pull request #4 from pojith/pojith-patch-4

 Heap sort

Author: pojith

Java/Algorithm/SortingAlgorithm/Heap sort

@@ -0,0 +1,85 @@
+import java.util.Arrays;
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class HeapSort {
+
+    // Function to perform heap sort
+    public static void heapSort(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[]
+    public static 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);
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        try {
+            System.out.print("Enter the number of elements: ");
+            int n = scanner.nextInt();
+            if (n <= 0) {
+                throw new IllegalArgumentException("Number of elements must be positive.");
+            }
+
+            int[] arr = new int[n];
+
+            System.out.println("Enter the elements:");
+            for (int i = 0; i < n; i++) {
+                arr[i] = scanner.nextInt();
+            }
+
+            System.out.println("Original array: " + Arrays.toString(arr));
+
+            heapSort(arr);
+
+            System.out.println("Sorted array: " + Arrays.toString(arr));
+        } catch (InputMismatchException e) {
+            System.out.println("Invalid input. Please enter integers only.");
+        } catch (IllegalArgumentException e) {
+            System.out.println(e.getMessage());
+        } finally {
+            scanner.close();
+        }
+    }
+}