add circular doubly linked list

Author: ashishyadav2

Java/src/datastructures/linkedList/DoublyCircularLL.java

@@ -0,0 +1,163 @@
+public class DoublyCircularLL {
+    static class Node {
+        private Node prev;
+        private Node next;
+        private int data;
+
+        Node(int data) {
+            this.data = data;
+        }
+    }
+
+    Node head = null;
+    Node tail = null;
+    private int size;
+
+    void addEmpty(int data) {
+        Node node = new Node(data);
+        head = tail = node;
+        node.prev = head;
+        node.next = head;
+        size++;
+    }
+
+    void addFront(int data) {
+        Node node = new Node(data);
+        if (head == null) {
+            addEmpty(data);
+        } else {
+            node.next = head;
+            tail.next = node;
+            node.prev = tail;
+            head = node;
+            size++;
+        }
+    }
+
+    void addEnd(int data) {
+        Node node = new Node(data);
+        if (tail == null) {
+            addEmpty(data);
+            return;
+        }
+        tail.next = node;
+        node.prev = tail;
+        node.next = head;
+        head.prev = node;
+        tail = node;
+        size++;
+    }
+
+    void addAt(int data, int index) {
+        Node getNode = get(index);
+        Node node = new Node(data);
+        if (index < 0 || index >= size) {
+            System.out.println("index: " + index + " is out of bound!");
+            return;
+        }
+        if (index == 0) {
+            addFront(data);
+            return;
+        }
+        if (index == size - 1) {
+            addEnd(data);
+            return;
+        }
+        node.next = getNode.next;
+        node.prev = getNode;
+        getNode.next.prev = node;
+        getNode.next = node;
+        size++;
+    }
+
+    Node get(int index) {
+        Node temp = head;
+        if (index < 0 || index >= size) {
+            return null;
+        }
+        for (int i = 0; i < index; i++) {
+            temp = temp.next;
+        }
+        return temp;
+    }
+
+    Node search(int item) {
+        Node temp = head;
+        while (temp != null) {
+            if (temp.data == item) {
+                return temp;
+            }
+            temp = temp.next;
+            if (temp == head) {
+                break;
+            }
+        }
+        return null;
+    }
+
+    int size() {
+        return size;
+    }
+
+    void removeFirst() {
+        if (head == tail) {
+            head = tail = null;
+            return;
+        }
+        head = head.next;
+        head.prev = tail;
+        tail.next = head;
+        size--;
+    }
+
+    void removeLast() {
+        if (head == tail) {
+            head = tail = null;
+            return;
+        }
+        tail = tail.prev;
+        tail.next = head;
+        head.prev = tail;
+        size--;
+    }
+
+    void deleteNode(int item) {
+        Node getNode = search(item);
+        if (getNode == head) {
+            removeFirst();
+            return;
+        }
+        if (getNode == tail) {
+            removeLast();
+            return;
+        }
+        getNode.prev.next = getNode.next;
+        getNode.next.prev = getNode.prev;
+        getNode = null;
+        size--;
+    }
+
+    void display() {
+        Node temp = head;
+        if (head == null) {
+            System.out.println("list is empty!");
+            return;
+        }
+        do {
+            System.out.print(temp.data + "-> ");
+            temp = temp.next;
+        } while (temp != head);
+        System.out.println("NULL" + " size: " + size());
+    }
+
+    public static void main(String[] args) {
+        DoublyCircularLL list = new DoublyCircularLL();
+        list.addFront(15);
+        list.addFront(19);
+        list.addEnd(48);
+        list.addEnd(57);
+        list.display();
+        list.addAt(69, 4);
+        list.display();
+    }
+}