Adding in more Algorithms and Data Structures implemented in Java

src/ArraySorting.java

@@ -4,30 +4,109 @@ import java.util.Random;
 public class ArraySorting {
     public static void main(String[] args) {
         Random rand = new Random();
-        int[] numbers = new int[100000000];
+        int[] numbers = new int[10];
+        int[] array = { 20, 30, 40, 50, 60, 70, 80, 90, 100 };
 
         for(int i = 0; i < numbers.length; i++) {
-            numbers[i] = rand.nextInt(10000);
+            numbers[i] = rand.nextInt(10);
         }
 
-        System.out.println("Before: ");
+//        System.out.println("Before: " + Arrays.toString(numbers));
-
+        int result = binarySearch(array, 0, array.length - 1, 40);
-
+//        quickSort(numbers);
 //        mergeSort(numbers, 0, numbers.length - 1);
 //        selectionSort(numbers);
 //        bubbleSort(numbers);
 //        Arrays.sort(numbers);
-//        insertionSort(numbers, 4, 8);
+//        insertionSort(numbers, 0, numbers.length);
-        System.out.println("After: ");
+//        System.out.println("After: " + Arrays.toString(numbers));
+        if (result == -1) {
+            System.out.println("Element not present");
+        } else {
+            System.out.println("Element found at index " + result);
+        }
     }
 
-    public static void quickSort(int[] numbers) {
+    private static int binarySearch(int[] array, int left, int right, int targetValue) {
+        if (right >= 1) {
+            int mid = 1 + (right - 1) / 2;
 
+            // If the element is present at the middle itself
+            if (array[mid] == targetValue) {
+                return mid;
+            }
+
+            // If the element is smaller than mid, hen it can only be present in left subarray
+            if (array[mid] > targetValue) {
+                return binarySearch(array, 1, mid - 1, targetValue);
+            }
+
+            // Else the element can only be present in the right subarray
+            return binarySearch(array, mid + 1, right, targetValue);
+        }
+
+        return -1;
     }
 
+    /* QUICK SORT ALGORITHM */
+
+    private static void swap(int[] array, int index1, int index2) {
+        int temp = array[index1];
+        array[index1] = array[index2];
+        array[index2] = temp;
+    }
+
+    private static int partition(int[] array, int lowIndex, int highIndex, int pivot) {
+        int leftPointer = lowIndex;
+        int rightPointer = highIndex;
+
+        while (leftPointer < rightPointer) {
+            while (array[leftPointer] <= pivot && leftPointer < rightPointer) {
+                leftPointer++;
+            }
+
+            while (array[rightPointer] >= pivot && leftPointer < rightPointer) {
+                rightPointer--;
+            }
+
+            swap(array, leftPointer, rightPointer);
+        }
+
+        if (array[leftPointer] > array[highIndex]) {
+            swap(array, leftPointer, highIndex);
+        } else {
+            leftPointer = highIndex;
+        }
+
+        return leftPointer;
+    }
+
+    private static void quickSort(int[] array) {
+        quickSort(array, 0, array.length - 1);
+    }
+
+    private static void quickSort(int[] array, int lowIndex, int highIndex) {
+
+        // Check to see if it's trying to sort a subarray of one item
+        if (lowIndex >= highIndex) {
+            return;
+        }
+
+        int pivotIndex = new Random().nextInt(highIndex - lowIndex) + lowIndex;
+        int pivot = array[pivotIndex];
+        swap(array, pivotIndex, highIndex);
+
+        int leftPointer = partition(array, lowIndex, highIndex, pivot);
+
+        quickSort(array, lowIndex, leftPointer - 1);
+        quickSort(array, leftPointer + 1, highIndex);
+    }
+
+    /* END: QUICK SORT ALGORITHM */
+
     /* MERGE SORT ALGORITHM */
 
-    public static void mergeSort(int[] array, int left, int right) {
+    private static void mergeSort(int[] array, int left, int right) {
         if(left < right) {
             int mid = (left+right) / 2; // Find the middle element
             mergeSort(array, left, mid); // Sort the first half
@@ -35,7 +114,8 @@ public class ArraySorting {
             merge(array, left, mid, right); // Merge the sorted halves
         }
     }
-    public static void merge(int[] array, int left, int mid, int right) {
+
+    private static void merge(int[] array, int left, int mid, int right) {
         // Find sizes of two subarrays to be merged
         int n1 = mid - left + 1;
         int n2 = right - mid;

src/CircularLinkedList.java

@@ -0,0 +1,93 @@
+public class CircularLinkedList {
+
+    public int size = 0;
+    public Node head = null;
+    public Node tail = null;
+
+    public static void main(String[] args) {
+        CircularLinkedList myList = new CircularLinkedList();
+        myList.addNodeToHead(75);
+        myList.addNodeToHead(50);
+        myList.addNodeToHead(25);
+        myList.print();
+        myList.addNodeToTail(100);
+        myList.print();
+        myList.rotateElement();
+        myList.print();
+        myList.deleteNodeFromTail();
+        myList.print();
+        myList.deleteNodeFromHead();
+        myList.print();
+
+    }
+
+    // Add a new Node at the start of the Linked List
+    public void addNodeToHead(int element) {
+        Node n = new Node(element);
+
+        if (size == 0) {
+            head = n;
+            tail = n;
+        } else {
+            n.next = head;
+            head = n;
+            tail.next = head;
+        }
+
+        size++;
+    }
+
+    // Add a new Node to the Tail of the Linked List
+    public void addNodeToTail(int element) {
+        if (size == 0) {
+            addNodeToHead(element);
+        } else {
+            Node n = new Node(element);
+            tail.next = n;
+            tail = n;
+            tail.next = head;
+            size++;
+        }
+    }
+
+    public void rotateElement() {
+        System.out.println("Rotating!");
+        tail = head;
+        head = head.next;
+    }
+
+    public void deleteNodeFromTail() {
+        System.out.println("\nDeleting Node " + tail.element + " from Tail");
+
+        if (tail.next == tail) {
+            tail = null;
+        }
+
+        Node newTail = tail;
+
+        while (newTail.next != tail) {
+            newTail = newTail.next;
+        }
+
+        newTail.next = tail.next;
+        tail = newTail;
+    }
+
+    public void deleteNodeFromHead() {
+        head = head.next;
+        tail.next = head;
+        size--;
+    }
+
+    public void print() {
+        System.out.println("The List so far: ");
+        Node temp = head;
+
+        do {
+            System.out.print(" " + temp.element);
+            temp = temp.next;
+        } while (temp != head);
+
+        System.out.println();
+    }
+}

src/JavaLinkedList.java

@@ -0,0 +1,20 @@
+import java.util.LinkedList;
+
+public class JavaLinkedList {
+    public static void main(String[] args) {
+        LinkedList<String> myList = new LinkedList<>();
+
+        myList.add("I");
+        myList.add("S");
+        myList.add("T");
+        System.out.println("Linked List: " + myList);
+        myList.addFirst("L");
+        myList.addLast("9");
+        System.out.println("Updated Linked List: " + myList);
+        myList.remove("9");
+        System.out.println("After Removal: " + myList);
+        String item = myList.get(2);
+        myList.set(2, item + " Changed");
+        System.out.println("After the change: " + myList);
+    }
+}

src/LinkedList.java

@@ -0,0 +1,77 @@
+import java.util.NoSuchElementException;
+
+public class LinkedList implements Stack {
+    public static void main(String[] args) {
+        int item;
+
+        LinkedList items = new LinkedList();
+
+        item = 25;
+
+        for (int i = item; i < 150; i++) {
+            items.push(i + 5);
+        }
+
+        // Is the stack empty?
+        if (items.isEmpty()) {
+            System.out.println("Empty Stack");
+        } else {
+            // Peek at the top
+            System.out.println("Peeking at the top: " + items.peek());
+
+            // Show the size
+            System.out.println("Size of the Stack: " + items.size());
+
+            // Pop off the top item
+            System.out.println("Popping off the top item: " + items.pop());
+        }
+    }
+    private static class Node {
+        int item;
+        Node next;
+
+        public Node(int current) {
+            item = current;
+        }
+    }
+
+    public LinkedList() {
+        top = null;
+    }
+
+    private Node top;
+
+    public void push(int current) {
+        Node c = new Node(current);
+        c.next = top;
+        top = c;
+    }
+
+    public int pop() {
+        int returnItem;
+        returnItem = top.item;
+        top = top.next;
+        return returnItem;
+    }
+
+    public boolean isEmpty() {
+        return top == null;
+    }
+
+    public int size() {
+        int counter = 0;
+        for (Node node = top; node != null; node = node.next) {
+            counter++;
+        }
+
+        return counter;
+    }
+
+    public int peek() {
+        if (top == null) {
+            throw new NoSuchElementException();
+        }
+
+        return top.item;
+    }
+}

src/Node.java

@@ -0,0 +1,8 @@
+public class Node {
+    int element;
+    Node next;
+
+    public Node(int element) {
+        this.element = element;
+    }
+}

src/Stack.java

@@ -0,0 +1,16 @@
+public interface Stack {
+    // Add to Top
+    void push(int item);
+    
+    // Remove from the top
+    int pop();
+    
+    // Look at the first item
+    int peek();
+    
+    // How many elements
+    int size();
+    
+    // Is the stack empty
+    boolean isEmpty();
+}