Implementation of Deque using Doubly Linked List in Python Last Updated : 08 Feb, 2025 Summarize Suggest changes Share Like Article Like Report A deque (double-ended queue) is a linear data structure that allows insertion and deletion from both the front and rear efficiently. A Doubly Linked List (DLL) is a preferred choice for implementing a deque as it enables O(1) insertion and deletion without shifting elements, unlike lists. Node StructureA Doubly Linked List consists of nodes where each node contains:Data (the value stored)Pointer to the next nodePointer to the previous node Python class Node: def __init__(self, key): self.key = key self.next = None self.prev = None Operations Explained1. Insertion at Rear (insert_rear(x)):Creates a new node and inserts it at the rear.Updates pointers accordingly.2. Deletion from Front (delete_front()):Removes the front node and updates pointers.Returns None if the deque is empty.3. Displaying Deque (display()):Traverses the list from front to rear and returns elements.4. Checking Size (get_size()):Returns the number of elements in the deque.5. Checking if Empty (is_empty()):Returns True if the deque is empty, otherwise FalseDeque Implementation Using Doubly Linked List Python class Node: def __init__(self, key): self.key = key self.next = None self.prev = None class MyDeque: def __init__(self): self.front = None self.rear = None self.size = 0 def insert_rear(self, x): temp = Node(x) if self.rear is None: self.front = self.rear = temp else: self.rear.next = temp temp.prev = self.rear self.rear = temp self.size += 1 def delete_front(self): if self.front is None: return None else: res = self.front.key self.front = self.front.next if self.front is None: self.rear = None else: self.front.prev = None self.size -= 1 return res def get_size(self): return self.size def is_empty(self): return self.size == 0 def display(self): temp = self.front elements = [] while temp: elements.append(temp.key) temp = temp.next return elements # Example Usage dq = MyDeque() dq.insert_rear(10) dq.insert_rear(20) dq.insert_rear(30) print("Deque after insertions:", dq.display()) print("Deleted from front:", dq.delete_front()) print("Deque after deletion:", dq.display()) OutputDeque after insertions: [10, 20, 30] Deleted from front: 10 Deque after deletion: [20, 30] Complexity AnalysisOperationTime ComplexityInsert at FrontO(1)Insert at RearO(1)Delete from FrontO(1)Delete from RearO(1)Get SizeO(1)Check if EmptyO(1)Display ElementsO(n) Advertise with us Next Article Implementation of Deque using Doubly Linked List in Python B brijkan3mz4 Follow Similar Reads Python Tutorial - Learn Python Programming Language Python is one of the most popular programming languages. 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