reverse the DLL iteratively and recursively.

Write a C function to reverse a given Doubly Linked List

See below diagrams for example.

     (a) Original Doubly Linked List  

     (b) Reversed Doubly Linked List  

//Assume that the head and tail pointers are made global , and so is available to the function.

// Iteratively...

void reverseListIteratively()

{

struct node *temp,*p=NULL;

p=head;

while(1)

{

temp=p->left;

p->left=p->right;

p->right=temp;

if((p->right)==NULL)

{

tail=p;

}

if((p->left)==NULL)

{

head=p;

}

p=p->left;

if(p==NULL)

{

break;

}

}

}

// recursively....

void reverseListRecursively(struct node *p)
{
struct node *temp=NULL;

if(p==NULL)
return;

temp=p->left;
p->left=p->right;
p->right=temp;

if((p->right)==NULL)
{
tail=p;
}
if((p->left)==NULL)
{
head=p;
}

reverseListRecursively(p->left);


}