Rename HeapSort.java to Sorts/HeapSort.java

Sorts/HeapSort.java

@@ -0,0 +1,174 @@
+import java.util.Scanner;
+
+/**
+ * Heap Sort Algorithm
+ * Implements MinHeap
+ * 
+ * @author Unknown
+ *
+ */
+public class HeapSort {
+    /** Array to store heap */
+    private int[] heap;
+    /** The size of the heap */
+    private int size;
+
+    /**
+     * Constructor
+     * 
+     * @param heap array of unordered integers
+     */
+    public HeapSort(int[] heap) {
+        this.setHeap(heap);
+        this.setSize(heap.length);
+    }
+
+    /**
+     * Setter for variable size
+     *  
+     * @param length new size
+     */
+    private void setSize(int length) {
+        this.size = length;
+    }
+
+    /**
+     * Setter for variable heap
+     * 
+     * @param heap array of unordered elements
+     */
+    private void setHeap(int[] heap) {
+        this.heap = heap;
+    }
+
+    /**
+     * Swaps index of first with second
+     * 
+     * @param first First index to switch
+     * @param second Second index to switch
+     */
+    private void swap(int first, int second) {
+        int temp = this.heap[first];
+        this.heap[first] = this.heap[second];
+        this.heap[second] = temp;
+    }
+
+    /**
+     * Heapifies subtree from top as root to last as last child
+     * 
+     * @param rootIndex index of root
+     * @param lastChild index of last child
+     */
+    private void heapSubtree(int rootIndex, int lastChild) {
+        int leftIndex = rootIndex * 2 + 1; 
+        int rightIndex = rootIndex * 2 + 2;
+        int root = this.heap[rootIndex];
+        if (rightIndex <= lastChild) { // if has right and left children
+            int left = this.heap[leftIndex]; 
+            int right = this.heap[rightIndex]; 
+            if (left < right && left < root) {
+                this.swap(leftIndex, rootIndex); 
+                this.heapSubtree(leftIndex, lastChild);
+            } else if (right < root) {
+                this.swap(rightIndex, rootIndex);
+                this.heapSubtree(rightIndex, lastChild);
+            }
+        } else if (leftIndex <= lastChild) { // if no right child, but has left child
+            int left = this.heap[leftIndex];
+            if (left < root) {
+                this.swap(leftIndex, rootIndex);
+                this.heapSubtree(leftIndex, lastChild);
+            }
+        }
+    }
+
+    /**
+     * Makes heap with root as root
+     * 
+     * @param root index of root of heap
+     */
+    private void makeMinHeap(int root) {
+        int leftIndex = root * 2 + 1; 
+        int rightIndex = root * 2 + 2; 
+        boolean hasLeftChild = leftIndex < this.heap.length;
+        boolean hasRightChild = rightIndex < this.heap.length;
+        if (hasRightChild) { //if has left and right
+            this.makeMinHeap(leftIndex);
+            this.makeMinHeap(rightIndex);
+            this.heapSubtree(root, this.heap.length - 1);
+        } else if (hasLeftChild) {
+            this.heapSubtree(root, this.heap.length - 1);
+        }
+    }
+
+    /**
+     * Gets the root of heap
+     *
+     * @return root of heap
+     */
+    private int getRoot() {
+        this.swap(0, this.size - 1);
+        this.size--;
+        this.heapSubtree(0, this.size - 1);
+        return this.heap[this.size]; // return old root
+    }
+
+    /**
+     * Sorts heap with heap sort; displays ordered elements to console.
+     * 
+     * @return sorted array of sorted elements
+     */
+    public final int[] sort() {
+        this.makeMinHeap(0); // make min heap using index 0 as root.
+        int[] sorted = new int[this.size];
+        int index = 0;
+        while (this.size > 0) {
+            int min = this.getRoot();
+            sorted[index] = min;
+            index++;
+        }
+        return sorted;
+    }
+
+    /**
+     * Gets input to sort
+     *
+     * @return unsorted array of integers to sort
+     */
+    public static int[] getInput() {
+        final int numElements = 6;
+        int[] unsorted = new int[numElements];
+        Scanner input = new Scanner(System.in);
+        System.out.println("Enter any 6 Numbers for Unsorted Array : ");
+        for (int i = 0; i < numElements; i++) {
+            unsorted[i] = input.nextInt();
+        }
+        input.close();
+        return unsorted;
+    }
+
+    /**
+     * Prints elements in heap
+     *
+     * @param heap array representing heap
+     */
+    public static void printData(int[] heap) {
+        System.out.println("Sorted Elements:");
+        for (int i = 0; i < heap.length; i++) {
+            System.out.print(" " + heap[i] + " ");
+        }
+    }
+
+    /**
+     * Main method
+     *
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        int[] heap = getInput();
+        HeapSort data = new HeapSort(heap);
+        int[] sorted = data.sort();
+        printData(sorted);
+    }
+
+}