CareerCup

private static void printDLLReverse(DLLNode head) {
		DLLNode current=head;
		DLLNode prev=head;
		
		while(current!=null)
		{
			prev=current;
			current=current.getNext();
		}
		
		while(prev!=null)
		{
			System.out.println(prev.getData());
			prev=prev.getPrevious();
		}
	}

node structure ->

1. previous node link called previous
2. next node link called next
3. data
---------------

Algo:
1. start
2. set temp to next
3. set next to prev
4. set prev to temp
5. advance current position (var pointing to the current position in the list) to next node
6. start from step 2 again

node structure ->

1. previous node link called previous
2. next node link called next
3. data
---------------

Algo:
1. start
2. set temp to next
3. set next to prev
4. set prev to temp
5. advance current position (var pointing to the current position in the list) to next node
6. start from step 2 again

dll * reverseDoubleLinkList(dll* x)
{
if(x == NULL)
return x;

dll * tmp = x->prev;
x->prev = x->next;
x->next = tmp;

if(x->prev)
return reverseDoubleLinkList(x->prev);
else
return x;


}

Change head of link list to last node and link list is in reversed

Best way to reverse DLL is to swap next and prev of each node. And at the end give *hRef to last node.

def reverseDoublyLinkedList(head):
    # head far left end, 0 or 1 node
    if head == None or (head.next==None and head.back==None):
        return

    cur = head
    # while there is another node to the right. swap the pointer values, assumes valid lists.
    while cur:
        tmp = cur.next
        cur.next = cur.back
        cur.back = tmp
        cur = tmp

why to reverse?? just go to end and back track

do like this

#define next prev
#define prev next
#define head tail
#define tail head

now use normal linklist traversal programs