// Add a node at the end of the list
void append(int new_data)
{
/* 1. allocate node
* 2. put in the data */
Node new_node = new Node(new_data);
Node last = head; /* used in step 5*/
/* 3. This new node is going to be the last node, so
* make next of it as NULL*/
new_node.next = null;
/* 4. If the Linked List is empty, then make the new
* node as head */
if (head == null) {
new_node.prev = null;
head = new_node;
return;
}
/* 5. Else traverse till the last node */
while (last.next != null)
last = last.next;
/* 6. Change the next of last node */
last.next = new_node;
/* 7. Make last node as previous of new node */
new_node.prev = last;
}