Create LinkedListReverseDouble

LinkedListReverseDouble

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+// Java program to reverse a doubly linked list
+
+class LinkedList {
+
+	static Node head;
+
+	static class Node {
+
+		int data;
+		Node next, prev;
+
+		Node(int d)
+		{
+			data = d;
+			next = prev = null;
+		}
+	}
+
+	/* Function to reverse a Doubly Linked List */
+	void reverse()
+	{
+		Node temp = null;
+		Node current = head;
+
+		/* swap next and prev for all nodes of
+		doubly linked list */
+		while (current != null) {
+			temp = current.prev;
+			current.prev = current.next;
+			current.next = temp;
+			current = current.prev;
+		}
+
+		/* Before changing head, check for the cases like
+		empty list and list with only one node */
+		if (temp != null) {
+			head = temp.prev;
+		}
+	}
+
+	/* UTILITY FUNCTIONS */
+	/* Function to insert a node at the beginning of the
+	* Doubly Linked List */
+	void push(int new_data)
+	{
+		/* allocate node */
+		Node new_node = new Node(new_data);
+
+		/* since we are adding at the beginning,
+		prev is always NULL */
+		new_node.prev = null;
+
+		/* link the old list off the new node */
+		new_node.next = head;
+
+		/* change prev of head node to new node */
+		if (head != null) {
+			head.prev = new_node;
+		}
+
+		/* move the head to point to the new node */
+		head = new_node;
+	}
+
+	/* Function to print nodes in a given doubly linked list
+	This function is same as printList() of singly linked
+	list */
+	void printList(Node node)
+	{
+		while (node != null) {
+			System.out.print(node.data + " ");
+			node = node.next;
+		}
+	}
+
+	public static void main(String[] args)
+	{
+		LinkedList list = new LinkedList();
+
+		/* Let us create a sorted linked list to test the
+		functions Created linked list will be 10->8->4->2
+	*/
+		list.push(2);
+		list.push(4);
+		list.push(8);
+		list.push(10);
+
+		System.out.println("Original linked list ");
+		list.printList(head);
+
+		list.reverse();
+		System.out.println("");
+		System.out.println("The reversed Linked List is ");
+		list.printList(head);
+	}
+}
+
+// This code has been contributed by KJ