Deque

O(1)
addFirst, addLast, removeFirst, removeLast

Python

	# Stack
	s = deque()
	s.append(1); # 1
	s.append(2); # 1,2
	s.append(3); # 1,2,3
	s.pop(); # 1,2
	s.pop(); # 1

view raw DequeAsStack.py hosted with ❤ by GitHub

	# Queue
	q = deque()
	q.append(1); # 1
	q.append(2); # 1,2
	q.append(3); # 1,2,3
	q.popleft(); # 2,3
	q.popleft(); # 3

view raw DequeAsQueue.py hosted with ❤ by GitHub

	# LinkedList
	ll = deque()
	ll.append(1); # 1
	ll.append(2); # 1,2
	ll.appendleft(0); # 0,1,2
	ll.pop(); # 0,1
	ll.popleft(); # 1

view raw DequeAsLinkedList.py hosted with ❤ by GitHub

Java

	// Stack
	Deque<Integer> s = new ArrayDeque<>();
	s.addLast(1); // 1
	s.addLast(2); // 1,2
	s.addLast(3); // 1,2,3
	s.removeLast(); // 1,2
	s.removeLast(); // 1

view raw DequeAsStack.java hosted with ❤ by GitHub

	// Queue
	Deque<Integer> q = new ArrayDeque<>();
	q.addLast(1); // 1
	q.addLast(2); // 1,2
	q.addLast(3); // 1,2,3
	q.removeFirst(); // 2,3
	q.removeFirst(); // 3

view raw DequeAsQueue.java hosted with ❤ by GitHub

	// LinkedList
	Deque<Integer> ll = new ArrayDeque<>();
	ll.addLast(1); // 1
	ll.addLast(2); // 1,2
	ll.addFirst(0); // 0,1,2
	ll.removeLast(); // 0,1
	ll.removeFirst(); // 1

view raw DequeAsLinkedList.java hosted with ❤ by GitHub

Tricks

Deque