what is Dequeue in data structure

A  de-queue  is  kind of queue  in which elements can be added or removed from the  either end but  not from the middle . the  term de-queue    is taken from  double ended Q.

There are two types of de-queue

1.

Input restricted de-queue  —

this queue allows  insertion only at one end but allow deletion  at both ends .

2. Output restricted de-queue  —

This  queue allow  insertion at both ends but deletions only  at one end.

Algorithm  for input restricted dequeue.

Step1 [check for under flow condition]

if front = -1 & rear  = -1, then

output  underflow & exit

Step2  [delete element at the front end ]

if [front]  >= 0 then

then  =Q[front]

Step3  [check queue  for empty]

if front  =  rear, then

rear = -1

front = -1

else

front = front+1

Step4  [delete element at the rear end ]

if  rear > = 0

item   =  Q[rear]

Step5 [check queue for empty ]

if front = rear, then

front = -1

rear = -1

else

rear = rear – 1

Step6   exit

Algorithm for output restricted dequeue

Step1 [check for  overflow condition]

If front  = 0 & rear >= size -1

Output over flow & exit

Step2 :  [check front pointer value]

If front >0, then

Front = front -1

Step3:  [insert  element at the front end ]

Q[front] = value

Step4 :  [ check rear pointer value]

If rear < size-1

Rear  = rear+1

Step5:  [ insert element at the rear end]

Q[rear] = value

Step6 : exit

Scroll Up