added code for reversing doubly linked list

Data Structure and Algorithm/Linkedlist/reversing DoublyLL.cpp

@@ -0,0 +1,85 @@
+/* C++ program to reverse a doubly linked list */
+#include <bits/stdc++.h>
+using namespace std;
+
+
+class Node
+{
+	public:
+	int data;
+	Node *next;
+	Node *prev;
+};
+
+
+void reverse(Node **head_ref)
+{
+	Node *temp = NULL;
+	Node *current = *head_ref;
+
+
+	while (current != NULL)
+	{
+		temp = current->prev;
+		current->prev = current->next;
+		current->next = temp;			
+		current = current->prev;
+	}
+
+	if(temp != NULL )
+		*head_ref = temp->prev;
+}
+
+
+
+
+void push(Node** head_ref, int new_data)
+{
+
+	Node* new_node = new Node();
+
+
+	new_node->data = new_data;
+
+
+	new_node->prev = NULL;
+
+	new_node->next = (*head_ref);	
+
+
+	if((*head_ref) != NULL)
+	(*head_ref)->prev = new_node ;
+
+	(*head_ref) = new_node;
+}
+
+void printList(Node *node)
+{
+	while(node != NULL)
+	{
+		cout << node->data << " ";
+		node = node->next;
+	}
+}
+
+/* Driver code */
+int main()
+{
+
+	Node* head = NULL;
+
+	push(&head, 2);
+	push(&head, 4);
+	push(&head, 8);
+	push(&head, 10);
+
+	cout << "Original Linked list" << endl;
+	printList(head);
+
+	reverse(&head);
+
+	cout << "\nreversed Linked list" << endl;
+	printList(head);		
+
+	return 0;
+}