#include <stdio.h>
#include <conio.h>
#include <alloc.h>
struct node
{
int data ;
struct node *link ;
} ;
struct dqueue
{
struct node *front ;
struct node *rear ;
} ;
void initdqueue ( struct dqueue * ) ;
void addqatend ( struct dqueue *, int item ) ;
void addqatbeg ( struct dqueue *, int item ) ;
int delqatbeg ( struct dqueue * ) ;
int delqatend ( struct dqueue * ) ;
void display ( struct dqueue ) ;
int count ( struct dqueue ) ;
void deldqueue ( struct dqueue * ) ;
void main( )
{
struct dqueue dq ;
int i, n ;
clrscr( ) ;
initdqueue ( &dq ) ;
addqatend ( &dq, 11 ) ;
addqatbeg ( &dq, 10 ) ;
addqatend ( &dq, 12 ) ;
addqatbeg ( &dq, 9 ) ;
addqatend ( &dq, 13 ) ;
addqatbeg ( &dq, 8 ) ;
addqatend ( &dq, 14 ) ;
addqatbeg ( &dq, 7 ) ;
display ( dq ) ;
n = count ( dq ) ;
printf ( "\nTotal elements: %d", n ) ;
i = delqatbeg ( &dq ) ;
printf ( "\nItem extracted = %d", i ) ;
i = delqatbeg ( &dq ) ;
printf ( "\nItem extracted = %d", i ) ;
i = delqatbeg ( &dq ) ;
printf ( "\nItem extracted = %d", i ) ;
i = delqatend ( &dq ) ;
printf ( "\nItem extracted = %d", i ) ;
display ( dq ) ;
n = count ( dq ) ;
printf ( "\nElements Left: %d", n ) ;
deldqueue ( &dq ) ;
getch( ) ;
}
/* initializes elements of structure */
void initdqueue ( struct dqueue *p )
{
p -> front = p -> rear = NULL ;
}
/* adds item at the end of dqueue */
void addqatend ( struct dqueue *p, int item )
{
struct node *temp ;
temp = ( struct node * ) malloc ( sizeof ( struct node ) );
temp -> data = item ;
temp -> link = NULL ;
if ( p -> front NULL )
return ;
while ( p -> front != NULL )
{
temp = p -> front ;
p -> front = p -> front -> link ;
free ( temp ) ;
}
}
Explain The merits of using a deque to implement a stack in data structure
please read data structure (schaum series) books
A double ended queue (or deque ) is a queue where insertion and deletion can be performed at both end that is front pointer can be used for insertion (apart from its usual operation i.e. deletion) and rear pointer can be used for deletion (apart from its usual operation i.e. insertion). So when we need to insert or delete at both end we need deque.
The queue is a linear data structure where operations of insertion and deletion are performed at separate ends also known as front and rear. Queue is a FIFO structure that is first in first out. Following are the types of queue: Linear queue Circular queue Priority queue Double ended queue ( or deque )
//implement double ended queue using array. #include<stdio.h> #include<conio.h> #define SIZE 20 typedef struct dq_t { int front,rear; int item[SIZE]; }deque; /********** Function Declaration begins **********/ void create(deque *); void display(deque *); void insert_rear(deque *, int); void insert_front(deque *, int); int delete_front(deque *, int); int delete_rear(deque *, int); /********** Function Declaration ends **********/ void main() { int data,ch,x; deque DQ; clrscr(); create(&DQ); printf("\n\t\t Program shows working of double ended queue"); do { printf("\n\t\t Menu"); printf("\n\t\t 1: insert at rear end"); printf("\n\t\t 2: insert at front end"); printf("\n\t\t 3: delete from front end"); printf("\n\t\t 4: delete from rear end"); printf("\n\t\t 5: exit. "); printf("\n\t\t Enter choice :"); scanf("%d",&ch); switch(ch) { case 1: if (DQ.rear >= SIZE) { printf("\n Deque is full at rear end"); continue; } else { printf("\n Enter element to be added at rear end :"); scanf("%d",&data); insert_rear(&DQ,data); printf("\n Elements in a deque are :"); display(&DQ); continue; } case 2: if (DQ.front <=0) { printf("\n Deque is full at front end"); continue; } else { printf("\n Enter element to be added at front end :"); scanf("%d",&data); insert_front(&DQ,data); printf("\n Elements in a deque are :"); display(&DQ); continue; } case 3: x = delete_front(&DQ,data); if (DQ.front==0) { continue; } else { printf("\n Elements in a deque are :"); display(&DQ); continue; } case 4: x = delete_rear(&DQ,data); if (DQ.rear==0) { continue; } else { printf("\n Elements in a deque are :"); display(&DQ); continue; } case 5: printf("\n finish"); return; } } while(ch!=5); getch(); } /********** Creating an empty double ended queue **********/ /********** Function Definition begins **********/ void create(deque *DQ) { DQ->front=0; DQ->rear =0; } /********** Function Definition ends **********/ /********** Inserting element at rear end **********/ /********** Function Definition begins **********/ void insert_rear(deque *DQ, int data) { if ((DQ->front 0) { printf("\n Underflow"); return(0); } else { DQ->rear = DQ->rear -1; data = DQ->item[DQ->rear]; printf("\n Element %d is deleted from rear:",data); } if (DQ->front==DQ->rear) { DQ->front =0; DQ->rear = 0; printf("\n Deque is empty(rear end)"); } return data; } /********** Function Definition ends **********/ /********** Displaying elements of DEQUE **********/ /********** Function Definition begins **********/ void display(deque *DQ) { int x; for(x=DQ->front;x<DQ->rear;x++) { printf("%d\t",DQ->item[x]); } printf("\n\n"); } /********** Function Definition ends **********/
You'll need to use a doubly-linked circular list, since otherwise when you pop off the tail element you'll need to whizz all the way round the list to find its predecessor. See the links section for an implementation of a doubly-linked circular list.
Explain The merits of using a deque to implement a stack in data structure
To efficiently implement a circular array in Python, you can use the collections.deque data structure. Deque allows for efficient insertion and deletion at both ends of the array, making it suitable for circular arrays. You can use the rotate() method to shift elements in the array, effectively creating a circular structure.
Queue is a data structure which is based on FIFO that is first in first out. Following are the types of queue: Linear queue Circular queue Priority queue Double ended queue ( or deque )
deque
The time complexity of deque operations in data structures is O(1), which means they have constant time complexity.
The C++ STL (Standard Template Library) provides a std::deque template specifically for this purpose: std::deque<int> deq {}; // default construct an empty deque of type int deq.push_back (42); // deq = {42} deq.push_front (0); // deq = {0, 42} deq.push_back (100); // deq = {0, 42, 100} deq.pop_front (); // deq = {42, 100} deq.pop_back (); // deq = {42} As with all other STL containers, any type or class that can be copy or move constructed can be placed in a std::deque, including other STL containers (even std::deque itself).
#include<deque> std::deque<int> deq; deq.push_back (42); deq.pop_back (); deq.push_front (0); deq.pop_front ();
please read data structure (schaum series) books
Danny Demanto's birth name is Daniel C. DeQue.
A double ended queue (or deque ) is a queue where insertion and deletion can be performed at both end that is front pointer can be used for insertion (apart from its usual operation i.e. deletion) and rear pointer can be used for deletion (apart from its usual operation i.e. insertion)
A double ended queue (or deque ) is a queue where insertion and deletion can be performed at both end that is front pointer can be used for insertion (apart from its usual operation i.e. deletion) and rear pointer can be used for deletion (apart from its usual operation i.e. insertion). So when we need to insert or delete at both end we need deque.