A deque is a data structure that allows both deletion as well as insertion of elements to be done at both ends of a queue. 
Consider the following code:

\(
\texttt{typedef $\cdots$ element ;}\\
\texttt{struct cell \{ element data; struct cell *next; \}}\\
\texttt{typedef struct \{ struct cell *front, *rear; \} deque;}
\)

\(\underline{\textbf{Implement}}\) the following operations \(\texttt{delete_rear}\) and \(\texttt{delete_front}\) that delete the rear (resp. front) element of a deque.

#include <stdio.h>
#include <stdlib.h>
typedef int element ;

struct cell { 
    element data; 
    struct cell *next; 
};

typedef struct { 
    struct cell *front, *rear; 
} deque;


deque CreateDeque()
{
    deque d;
	d.front = d.rear = NULL ;
	return d;
}

int isEmptyDeque(deque d)
{
    return d.front==NULL;
}

int EnqueueRear (deque *d, element item )
{
	struct cell *temp ;

	temp = ( struct cell * ) malloc ( sizeof ( struct cell )  );
	if(!temp) return 0;
	
	temp -> data = item ;
	temp -> next = NULL ;

	if ( d -> front == NULL )
		d -> front = temp ;
	else
		d -> rear -> next = temp ;
	d -> rear = temp ;
	return 1;
}

int EnqueueFront(deque *d, element item )
{
	struct cell *temp ;
	
	
	temp = ( struct cell * ) malloc ( sizeof ( struct cell )  );
	if(!temp) return 0;
	
	temp -> data = item ;
	temp -> next = NULL ;

	if ( d -> front == NULL )
		d -> front = d -> rear = temp ;
	else
	{
		temp -> next = d -> front ;
		d -> front = temp ;
	}
	return 1;
}

int DeleteFront (deque *d )
{
	struct cell *temp ;
	 
	if ( isEmptyDeque(*d) ) return 0 ;

	temp = d -> front ;
	d -> front = temp -> next ;
	free ( temp ) ;

	if ( temp == NULL )
		d -> rear = NULL ;
	
	return 1;
}

 
int DeleteRear(deque *d) 	
{
	struct cell *p ;
	if ( isEmptyDeque(*d) ) return 0 ;
	if (d->front == d->rear)
	{
		free(d->front);
		d->front = d->rear = NULL ;
		return 1 ;
	}
	p = d->front ;	 
	while (p->next != d->rear)						
		p = p->next;
	free(d->rear);
	p->next = NULL;
	d->rear = p;								
	return 1;							
}

int Front(deque d, element *e)
{
    if(isEmptyDeque(d)) return 0;
    *e=d.front->data;
    return 1;
}

int Rear(deque d, element *e)
{
    if(isEmptyDeque(d)) return 0;
    *e=d.rear->data;
    return 1;
}


void display (deque d )
{
	struct cell *temp = d.front ;

	printf ( "\nfront -> " ) ;
	while ( temp != NULL )
	{
		if ( temp -> next == NULL )
		{
			printf ( " %d", temp -> data ) ;
			printf ( " <- rear" ) ;
		}
		else
			printf ( " %d", temp -> data ) ;
		temp = temp -> next ;
	}
	printf ( "\n" ) ;
}


int main()
{
    deque d;
    int i;
    
    d=CreateDeque();
    
    for(i=1;i<10;i++)
    {
        EnqueueFront (&d, i );
        EnqueueRear (&d, i );
        display(d);
    }
    
    
    for(i=1;i<10;i++)
    {
        DeleteFront (&d);
        DeleteRear (&d);
        display(d);
    }
    
    return 0;
}