a$)$ struct node$\{$ node$*$prev; int val; node$*$next;$\}$; struct

Double$\_$Linked$\_$List$\{$node$*$ head; node$*$tall$\}$; void

dll$\_$method $($Double$\_$Linked$\_$List$*$ dll$)$;

The dll$\_$ method function has the following definition:

void dll$\_$method $($Double$\_$Linked$\_$List$*$ dll$)\{$

node$*$left$=$ dll$->$head;

node$*$right$=$ dll$->$tail;

while$($left $!=$ right && left$->$ prev!$=$ right$)\{$

swap$($left$->$val, right$->$val$)$;

left$=$left$->$next;

right$=$ right$->$prev;$\}\}$

i$)$ What does the dll$\_$method function do and how does the algorithm

work?

ii$)$ Determine the runtime formula using dashes in the code. N is the

number of elements in the list. Count all assignments and compare and

consider a suitable number for the swap function.

iii$)$ What is the complexity of the program in the best and worst case?