Page 519 - Computer science 868 Class 12
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4.  Following is the algorithm to delete an element from the rear end of the Queue.
                   int deleteRear(int qu[], int max, int front, int rear)
                   Step 1:  Start.

                   Step 2:  If rear = front then display “Empty from rear end..Dequeue Underflow”, return value
                   Step 3:  Decrement rear by 1

                   Step 4:  Return dqu[rear+1]
                   Step 5:  Accept cont
                   Step 6:  If cont=“Yes” or cont=“yes” then go to Step 3
                   Step 7:  Stop.

                 Let us write the Java code for the above operations.


                   Program 5     A class called DeQue is defined to perform operations on a Double ended queue. The details
                                 of the class are given below.
                                 Class name               :   DeQue
                                 Data Members
                                 ele[]                    :   an array to hold integer elements
                                 cap                      :   to store the capacity of the array
                                 front                    :   to point to the index of the front
                                 rear                     :   to point to the index of the rear
                                 Member Functions
                                 DeQue (int max)          :    constructor to initialise the data members cap = max, front = 0,
                                                              rear = 0 and create the integer array
                                 void pushfront(int v)    :     to add integers from the front index if possible else display
                                                              the message “full from front..overflow”
                                 void pushrear(int v)     :     to add integers from the rear index if possible else display the
                                                              message “full from rear..overflow”
                                 int popfront()           :     to remove  and  return element from the front, if array is
                                                              empty then return -999
                                 int poprear()            :     to remove and return element from the rear, if array is empty
                                                              then return -999
                                 void display()           :   to display the elements present in the dequeue
                                 Specify  the  class  DeQue  giving  details  of  the  constructor(int),  member  functions  void
                                 pushrear(int), pushfront(int), int popfront(), int poprear(), and void display().

                   1       import java.util.*;

                   2       class DeQue
                   3       { int ele[],front,rear,cap;
                   4         DeQue(int max)

                   5         { cap=max;

                   6           ele=new int[cap];
                   7           front=rear=0;





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