Deque o Double Ended Queue es una versión generalizada de la estructura de datos de Queue que permite insertar y eliminar en ambos extremos. En una publicación anterior, discutimos la introducción de deque. Ahora, en esta publicación, vemos cómo implementamos deque usando una array circular.
Operaciones en Deque:
Principalmente, las siguientes cuatro operaciones básicas se realizan en la cola:
- insertFront() : Agrega un elemento al frente de Deque.
- insertRear() : Agrega un elemento en la parte posterior de Deque.
- deleteFront() : Elimina un elemento del frente de Deque.
- deleteRear() : Elimina un elemento de la parte posterior de Deque.
Además de las operaciones anteriores, también se admiten las siguientes operaciones
- getFront() : Obtiene el elemento frontal de la cola.
- getRear() : Obtiene el último elemento de la cola.
- isEmpty() : Comprueba si Deque está vacío o no.
- isFull() : Comprueba si Deque está lleno o no.
Deque de implementación de array circular
Para implementar deque, necesitamos realizar un seguimiento de dos índices, delantero y trasero. Ponemos en cola (empujamos) un elemento en la parte trasera o delantera de la cola y sacamos de la cola (pop) un elemento tanto en la parte trasera como en la delantera.
Laboral :
Cree una array vacía ‘arr’ de tamaño ‘n’
initialize front = -1 , rear = 0
Insertar el primer elemento en deque, ya sea en la parte delantera o trasera, dará el mismo resultado.
Después de insertar Puntos delanteros = 0 y Puntos traseros = 0
Insertar elementos en el extremo trasero
a). First we check deque if Full or Not
b). IF Rear == Size-1
then reinitialize Rear = 0 ;
Else increment Rear by '1'
and push current key into Arr[ rear ] = key
Front remain same.
Insertar elementos en el extremo frontal
a). First we check deque if Full or Not
b). IF Front == 0 || initial position, move Front
to points last index of array
front = size - 1
Else decremented front by '1' and push
current key into Arr[ Front] = key
Rear remain same.
Eliminar elemento de la parte trasera
a). first Check deque is Empty or Not
b). If deque has only one element
front = -1 ; rear =-1 ;
Else IF Rear points to the first index of array
it's means we have to move rear to points
last index [ now first inserted element at
front end become rear end ]
rear = size-1 ;
Else || decrease rear by '1'
rear = rear-1;
Eliminar elemento del front-end
a). first Check deque is Empty or Not
b). If deque has only one element
front = -1 ; rear =-1 ;
Else IF front points to the last index of the array
it's means we have no more elements in array so
we move front to points first index of array
front = 0 ;
Else || increment Front by '1'
front = front+1;
A continuación se muestra la implementación de la idea anterior.
C++
// C++ implementation of De-queue using circular
// array
#include<iostream>
using namespace std;
// Maximum size of array or Dequeue
#define MAX 100
// A structure to represent a Deque
class Deque
{
int arr[MAX];
int front;
int rear;
int size;
public :
Deque(int size)
{
front = -1;
rear = 0;
this->size = size;
}
// Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool isEmpty();
int getFront();
int getRear();
};
// Checks whether Deque is full or not.
bool Deque::isFull()
{
return ((front == 0 && rear == size-1)||
front == rear+1);
}
// Checks whether Deque is empty or not.
bool Deque::isEmpty ()
{
return (front == -1);
}
// Inserts an element at front
void Deque::insertfront(int key)
{
// check whether Deque if full or not
if (isFull())
{
cout << "Overflow\n" << endl;
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// front is at first position of queue
else if (front == 0)
front = size - 1 ;
else // decrement front end by '1'
front = front-1;
// insert current element into Deque
arr[front] = key ;
}
// function to inset element at rear end
// of Deque.
void Deque ::insertrear(int key)
{
if (isFull())
{
cout << " Overflow\n " << endl;
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// rear is at last position of queue
else if (rear == size-1)
rear = 0;
// increment rear end by '1'
else
rear = rear+1;
// insert current element into Deque
arr[rear] = key ;
}
// Deletes element at front end of Deque
void Deque ::deletefront()
{
// check whether Deque is empty or not
if (isEmpty())
{
cout << "Queue Underflow\n" << endl;
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else
// back to initial position
if (front == size -1)
front = 0;
else // increment front by '1' to remove current
// front value from Deque
front = front+1;
}
// Delete element at rear end of Deque
void Deque::deleterear()
{
if (isEmpty())
{
cout << " Underflow\n" << endl ;
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else if (rear == 0)
rear = size-1;
else
rear = rear-1;
}
// Returns front element of Deque
int Deque::getFront()
{
// check whether Deque is empty or not
if (isEmpty())
{
cout << " Underflow\n" << endl;
return -1 ;
}
return arr[front];
}
// function return rear element of Deque
int Deque::getRear()
{
// check whether Deque is empty or not
if(isEmpty() || rear < 0)
{
cout << " Underflow\n" << endl;
return -1 ;
}
return arr[rear];
}
// Driver program to test above function
int main()
{
Deque dq(5);
cout << "Insert element at rear end : 5 \n";
dq.insertrear(5);
cout << "insert element at rear end : 10 \n";
dq.insertrear(10);
cout << "get rear element " << " "
<< dq.getRear() << endl;
dq.deleterear();
cout << "After delete rear element new rear"
<< " become " << dq.getRear() << endl;
cout << "inserting element at front end \n";
dq.insertfront(15);
cout << "get front element " << " "
<< dq.getFront() << endl;
dq.deletefront();
cout << "After delete front element new "
<< "front become " << dq.getFront() << endl;
return 0;
}
Java
// Java implementation of De-queue using circular
// array
// A structure to represent a Deque
class Deque
{
static final int MAX = 100;
int arr[];
int front;
int rear;
int size;
public Deque(int size)
{
arr = new int[MAX];
front = -1;
rear = 0;
this.size = size;
}
/*// Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool isEmpty();
int getFront();
int getRear();*/
// Checks whether Deque is full or not.
boolean isFull()
{
return ((front == 0 && rear == size-1)||
front == rear+1);
}
// Checks whether Deque is empty or not.
boolean isEmpty ()
{
return (front == -1);
}
// Inserts an element at front
void insertfront(int key)
{
// check whether Deque if full or not
if (isFull())
{
System.out.println("Overflow");
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// front is at first position of queue
else if (front == 0)
front = size - 1 ;
else // decrement front end by '1'
front = front-1;
// insert current element into Deque
arr[front] = key ;
}
// function to inset element at rear end
// of Deque.
void insertrear(int key)
{
if (isFull())
{
System.out.println(" Overflow ");
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// rear is at last position of queue
else if (rear == size-1)
rear = 0;
// increment rear end by '1'
else
rear = rear+1;
// insert current element into Deque
arr[rear] = key ;
}
// Deletes element at front end of Deque
void deletefront()
{
// check whether Deque is empty or not
if (isEmpty())
{
System.out.println("Queue Underflow\n");
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else
// back to initial position
if (front == size -1)
front = 0;
else // increment front by '1' to remove current
// front value from Deque
front = front+1;
}
// Delete element at rear end of Deque
void deleterear()
{
if (isEmpty())
{
System.out.println(" Underflow");
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else if (rear == 0)
rear = size-1;
else
rear = rear-1;
}
// Returns front element of Deque
int getFront()
{
// check whether Deque is empty or not
if (isEmpty())
{
System.out.println(" Underflow");
return -1 ;
}
return arr[front];
}
// function return rear element of Deque
int getRear()
{
// check whether Deque is empty or not
if(isEmpty() || rear < 0)
{
System.out.println(" Underflow\n");
return -1 ;
}
return arr[rear];
}
// Driver program to test above function
public static void main(String[] args)
{
Deque dq = new Deque(5);
System.out.println("Insert element at rear end : 5 ");
dq.insertrear(5);
System.out.println("insert element at rear end : 10 ");
dq.insertrear(10);
System.out.println("get rear element : "+ dq.getRear());
dq.deleterear();
System.out.println("After delete rear element new rear become : " +
dq.getRear());
System.out.println("inserting element at front end");
dq.insertfront(15);
System.out.println("get front element: " +dq.getFront());
dq.deletefront();
System.out.println("After delete front element new front become : " +
+ dq.getFront());
}
}
Python3
# Python implementation of De-queue using circular
# array
# A structure to represent a Deque
MAX = 100;
class Deque:
def __init__(self, size):
self.arr = [0] * MAX
self.front = -1;
self.rear = 0;
self.size = size;
''' Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool isEmpty();
int getFront();
int getRear(); '''
# Checks whether Deque is full or not.
def isFull(self):
return ((self.front == 0 and self.rear == self.size-1) or self.front == self.rear + 1)
# Checks whether Deque is empty or not.
def isEmpty (self):
return (self.front == -1);
# Inserts an element at front
def insertfront(self, key):
# check whether Deque if full or not
if (self.isFull()):
print("Overflow");
return;
# If queue is initially empty
if (self.front == -1):
self.front = 0;
self.rear = 0;
# front is at first position of queue
elif (self.front == 0):
self.front = self.size - 1 ;
else: # decrement front end by '1'
self.front = self.front-1;
# insert current element into Deque
self.arr[self.front] = key ;
# function to inset element at rear end
# of Deque.
def insertrear(self, key):
if (self.isFull()):
print(" Overflow");
return;
# If queue is initially empty
if (self.front == -1):
self.front = 0;
self.rear = 0;
# rear is at last position of queue
elif (self.rear == self.size-1):
self.rear = 0;
# increment rear end by '1'
else:
self.rear = self.rear+1;
# insert current element into Deque
self.arr[self.rear] = key ;
# Deletes element at front end of Deque
def deletefront(self):
# check whether Deque is empty or not
if (self.isEmpty()):
print("Queue Underflow");
return ;
# Deque has only one element
if (self.front == self.rear):
self.front = -1;
self.rear = -1;
else:
# back to initial position
if (self.front == self.size -1):
self.front = 0;
else: # increment front by '1' to remove current
# front value from Deque
self.front = self.front+1;
# Delete element at rear end of Deque
def deleterear(self):
if (self.isEmpty()):
print(" Underflow");
return ;
# Deque has only one element
if (self.front == self.rear):
self.front = -1;
self.rear = -1;
elif (self.rear == 0):
self.rear = self.size-1;
else:
self.rear = self.rear-1;
# Returns front element of Deque
def getFront(self):
# check whether Deque is empty or not
if (self.isEmpty()):
print(" Underflow");
return -1 ;
return self.arr[self.front];
# function return rear element of Deque
def getRear(self):
# check whether Deque is empty or not
if(self.isEmpty() or self.rear < 0):
print(" Underflow");
return -1 ;
return self.arr[self.rear];
# Driver program to test above function
dq = Deque(5);
print("Insert element at rear end : 5 ");
dq.insertrear(5);
print("insert element at rear end : 10 ");
dq.insertrear(10);
print(f"get rear element : {dq.getRear()}");
dq.deleterear();
print(f"After delete rear element new rear become : {dq.getRear()}");
print("inserting element at front end");
dq.insertfront(15);
print(f"get front element: {dq.getFront()}");
dq.deletefront();
print(f"After delete front element new front become : {dq.getFront()}");
# This code is contributed by _saurabh_jaiswal
C#
// C# implementation of De-queue using circular
// array
using System;
// A structure to represent a Deque
public class Deque
{
static readonly int MAX = 100;
int []arr;
int front;
int rear;
int size;
public Deque(int size)
{
arr = new int[MAX];
front = -1;
rear = 0;
this.size = size;
}
/*// Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool .Count!=0;
int getFront();
int getRear();*/
// Checks whether Deque is full or not.
bool isFull()
{
return ((front == 0 && rear == size - 1)||
front == rear + 1);
}
// Checks whether Deque is empty or not.
bool isEmpty ()
{
return (front == -1);
}
// Inserts an element at front
void insertfront(int key)
{
// check whether Deque if full or not
if (isFull())
{
Console.WriteLine("Overflow");
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// front is at first position of queue
else if (front == 0)
front = size - 1 ;
else // decrement front end by '1'
front = front - 1;
// insert current element into Deque
arr[front] = key ;
}
// function to inset element at rear end
// of Deque.
void insertrear(int key)
{
if (isFull())
{
Console.WriteLine(" Overflow ");
return;
}
// If queue is initially empty
if (front == -1)
{
front = 0;
rear = 0;
}
// rear is at last position of queue
else if (rear == size - 1)
rear = 0;
// increment rear end by '1'
else
rear = rear+1;
// insert current element into Deque
arr[rear] = key ;
}
// Deletes element at front end of Deque
void deletefront()
{
// check whether Deque is empty or not
if (isEmpty())
{
Console.WriteLine("Queue Underflow\n");
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else
// back to initial position
if (front == size - 1)
front = 0;
else // increment front by '1' to remove current
// front value from Deque
front = front + 1;
}
// Delete element at rear end of Deque
void deleterear()
{
if (isEmpty())
{
Console.WriteLine(" Underflow");
return ;
}
// Deque has only one element
if (front == rear)
{
front = -1;
rear = -1;
}
else if (rear == 0)
rear = size - 1;
else
rear = rear - 1;
}
// Returns front element of Deque
int getFront()
{
// check whether Deque is empty or not
if (isEmpty())
{
Console.WriteLine(" Underflow");
return -1 ;
}
return arr[front];
}
// function return rear element of Deque
int getRear()
{
// check whether Deque is empty or not
if (isEmpty() || rear < 0)
{
Console.WriteLine(" Underflow\n");
return -1 ;
}
return arr[rear];
}
// Driver code
public static void Main(String[] args)
{
Deque dq = new Deque(5);
Console.WriteLine("Insert element at rear end : 5 ");
dq.insertrear(5);
Console.WriteLine("insert element at rear end : 10 ");
dq.insertrear(10);
Console.WriteLine("get rear element : "+ dq.getRear());
dq.deleterear();
Console.WriteLine("After delete rear element new rear become : " +
dq.getRear());
Console.WriteLine("inserting element at front end");
dq.insertfront(15);
Console.WriteLine("get front element: " +dq.getFront());
dq.deletefront();
Console.WriteLine("After delete front element new front become : " +
+ dq.getFront());
}
}
// This code is contributed by aashish1995
Javascript
<script>
// Javascript implementation of De-queue using circular
// array
// A structure to represent a Deque
let MAX = 100;
class Deque
{
constructor(size)
{
this.arr = new Array(MAX);
this.front = -1;
this.rear = 0;
this.size = size;
}
/*// Operations on Deque:
void insertfront(int key);
void insertrear(int key);
void deletefront();
void deleterear();
bool isFull();
bool isEmpty();
int getFront();
int getRear();*/
// Checks whether Deque is full or not.
isFull()
{
return ((this.front == 0 && this.rear == this.size-1)||
this.front == this.rear+1);
}
// Checks whether Deque is empty or not.
isEmpty ()
{
return (this.front == -1);
}
// Inserts an element at front
insertfront(key)
{
// check whether Deque if full or not
if (this.isFull())
{
document.write("Overflow<br>");
return;
}
// If queue is initially empty
if (this.front == -1)
{
this.front = 0;
this.rear = 0;
}
// front is at first position of queue
else if (this.front == 0)
this.front = this.size - 1 ;
else // decrement front end by '1'
this.front = this.front-1;
// insert current element into Deque
this.arr[this.front] = key ;
}
// function to inset element at rear end
// of Deque.
insertrear(key)
{
if (this.isFull())
{
document.write(" Overflow <br>");
return;
}
// If queue is initially empty
if (this.front == -1)
{
this.front = 0;
this.rear = 0;
}
// rear is at last position of queue
else if (this.rear == this.size-1)
this.rear = 0;
// increment rear end by '1'
else
this.rear = this.rear+1;
// insert current element into Deque
this.arr[this.rear] = key ;
}
// Deletes element at front end of Deque
deletefront()
{
// check whether Deque is empty or not
if (this.isEmpty())
{
document.write("Queue Underflow<br>");
return ;
}
// Deque has only one element
if (this.front == this.rear)
{
this.front = -1;
this.rear = -1;
}
else
// back to initial position
if (this.front == this.size -1)
this.front = 0;
else // increment front by '1' to remove current
// front value from Deque
this.front = this.front+1;
}
// Delete element at rear end of Deque
deleterear()
{
if (this.isEmpty())
{
document.write(" Underflow<br>");
return ;
}
// Deque has only one element
if (this.front == this.rear)
{
this.front = -1;
this.rear = -1;
}
else if (this.rear == 0)
this.rear = this.size-1;
else
this.rear = this.rear-1;
}
// Returns front element of Deque
getFront()
{
// check whether Deque is empty or not
if (this.isEmpty())
{
document.write(" Underflow<br>");
return -1 ;
}
return this.arr[this.front];
}
// function return rear element of Deque
getRear()
{
// check whether Deque is empty or not
if(this.isEmpty() || this.rear < 0)
{
document.write(" Underflow<br>");
return -1 ;
}
return this.arr[this.rear];
}
}
// Driver program to test above function
let dq = new Deque(5);
document.write("Insert element at rear end : 5 <br>");
dq.insertrear(5);
document.write("insert element at rear end : 10 <br>");
dq.insertrear(10);
document.write("get rear element : "+ dq.getRear()+"<br>");
dq.deleterear();
document.write("After delete rear element new rear become : " +
dq.getRear()+"<br>");
document.write("inserting element at front end<br>");
dq.insertfront(15);
document.write("get front element: " +dq.getFront()+"<br>");
dq.deletefront();
document.write("After delete front element new front become : " +
+ dq.getFront()+"<br>");
// This code is contributed by avanitrachhadiya2155
</script>
Producción
Insert element at rear end : 5 insert element at rear end : 10 get rear element 10 After delete rear element new rear become 5 inserting element at front end get front element 15 After delete front element new front become 5
Complejidad de tiempo: la complejidad de tiempo de todas las operaciones como insertfront(), insertlast(), deletefront(), deletelast()is O(1) .
En la próxima publicación, discutiremos la implementación de deque utilizando la lista doblemente enlazada.
Este artículo es una contribución de Nishant Singh . Si te gusta GeeksforGeeks y te gustaría contribuir, también puedes escribir un artículo usando write.geeksforgeeks.org o enviar tu artículo por correo a review-team@geeksforgeeks.org. Vea su artículo que aparece en la página principal de GeeksforGeeks y ayude a otros Geeks.
Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA