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{{{ REVERSE(DoubleLinkList head) { DoubleLinkList prev,next,curr; prev = null; curr = head; while(curr != null) { next = curr.next; curr.next = prev; current.parent = next; prev = curr; curr = next; } return prev; - KEEG June 20, 2011 | Flag Reply

Basic Idea of reversing a linked list.
1. 3 pointers.(prev , cur, next)
2. In Each iteration,
a) next will be cur`s next
b) prev`s next will be cur
c) cur`s prev will be prev

- Psycho June 20, 2011 | Flag Reply

Yes..The correct one..

- Psycho June 20, 2011 | Flag Reply

Do we need to reverse the Doubly Linked list? I can simply change the Head to the last node.
As it is double linked, its done I think.
Please correct me if I am missing something.

- King@Work June 21, 2011 | Flag Reply

reverse(Node** head){

Node* node = *head;
Node* temp = NULL;

while(node != NULL){
temp = node->prev;
node->prev = node->next;
node->next = temp;
node = node->prev;
}

if(temp != NULL)
*head = temp->prev;

}

- Anonymous June 23, 2011 | Flag Reply

reverse node*(struct node *pHead)
{
struct node *r = NULL;
struct node *s = NULL;

while(pHead)
{
s = pHead->next;
pHead->next = r;

r = pHead;
pHead = s;
}
return r;
}

- Naidu June 27, 2011 | Flag Reply

#include<iostream>
using namespace std;

class node {
int data;
node *next;
node *prev;
public:
node()
{
data=0;
next=prev=NULL;
}
friend class ll;
};

class ll {
node *start;
public:
ll()
{
start=NULL;
}

void insert()
{
int num;
do {
cout<<"entr num 2 b inserted\n";
cin>>num;
if(num!=-1)
{
node *temp=new node;
temp->data=num;
temp->next=temp->prev=NULL;
if(start==NULL)
{
start=temp;
}
else
{
node *t=start;
while(t->next!=NULL)
t=t->next;
t->next=temp;
temp->prev=t;
temp->next=NULL;
}
}
else ;
}while(num!=-1);
}


void display()
{
node *t=start;
while(t)
{
cout<<t->data<<" ";
t=t->next;
}
cout<<endl;
}

void rev()
{
node *xx=NULL;
node *curr=start;
node *temp=NULL;
while(curr!=NULL)
{
temp=curr->next;
curr->next=xx;
curr->prev=temp;
xx=curr;
curr=temp;
}
start=xx;
}
};

int main()
{
ll l;
l.insert();
l.display();
l.rev();
l.display();
return 0;
}

- ashu July 24, 2011 | Flag Reply

<pre lang="" line="1" title="CodeMonkey76510" class="run-this"> public LLNode Reverse(LLNode node)
{
if (node == null || node.Next == null)
return node;
LLNode head = node, tmpNode = node;
while (tmpNode!=null)
{
tmpNode = head.Next.Next;
head.Next = head;
if (tmpNode != null)
head = tmpNode;
}
node.Next = null;
return head;
}</pre><pre title="CodeMonkey76510" input="yes">
</pre>

- Anonymous July 25, 2011 | Flag Reply

there are 3 ways :
1. create a new doubly linked list and copy the values with reversing the prev and next pointers
2. swap values of last with first, second-last with second and so on
3. change the head from first to last node and reverse the prev next.
Logically it does not make much difference except the head but when asked for reversing we shud consider the pointers next and prev

- aditya.bokaro August 08, 2011 | Flag Reply