Lecture 11

Learning objectives

After this class, you should be able to:

1. Given certain operations on a deque, implemented by a circular array, draw a figure that shows its state at the end of those operations.
2. Give the time complexity of the different operations on a deque.
3. Implement features of a deque.
4. Give applications where a deque can be useful.
5. Given certain operations on a stack or a queue, draw a figure that shows the state of the data structure at the end of those operations.
6. Give the time complexity of the different operations on a stack or a queue.
7. Implement features of a stack or a queue, using other data structures, such as deques or linked lists.
8. Give applications where stacks or queues can be useful.

Reading assignment

1. Section 3.8 (up to fig 3.27), class notes for deque implementation based on a circular array (do not use the text book's implementation, until the next lecture), Section 4.1-4.2, section 4.3 (the need for a priority queue).
2. Sec 4.4, 4.5.

Exercises and review questions

• Exercises and review questions on current lecture's material

  (Note: Use a deque implementation based on a circular array in all questions)

  1. Give a sequence of operations such that a deque looks as shown in the figure below. Also give the array positions corresponding to the beginning and end of the deque.

     a

     b

  2. Let us assume a deque has the following data:

     c

     d

     a

     b

     and we now try to push_front an 'e'. Show how the deque will look like after this insert operation.

  3. Implement the back member function of a deque.
  4. Implement the front member function of a deque.
  5. Implement the push_back member function of a deque.
  6. Implement the pop_back member function of a deque.
  7. Implement the pop_front member function of a deque.
  8. Implement the [] operator of a deque.
  9. If a deque looked liked in the question 2, and we push_front an e, but want the new deque to look like:

     e

     a

     b

     c

     d

     then how should the push_front code be changed? Note that this is a different implementation of a deque.

  10. Give a real-world application for deques. (Post your answer on the discussion board)
  11. Let us perform the following operations on a stack: push(3), push(2), push(1), pop(). Draw a figure to show the state of the stack. If the underlying data structure were a deque, with initial capacity 2, then show the final state of the deque too. If the underlying data structure were a doubly-linked list, then show the final state of the list too.
  12. Let us perform the following operations on a queue: push(3), push(2), push(1), pop(). Draw a figure to show the state of the queue. If the underlying data structure were a deque, with initial capacity 2, then show the final state of the deque too. If the underlying data structure were a doubly-linked list, then show the final state of the list too.
  13. Will it be efficient to implement a stack using a vector?
  14. Will it be efficient to implement a queue using a vector?
  15. Will it be efficient to implement a stack using a singly linked list?
  16. Will it be efficient to implement a queue using a singly linked list?
  17. Show an implementation of a stack's pop and push functions, where the underlying data structure is a doubly linked list.
  18. Give a real-world application for (i) stacks and (ii) queues. (Post your answer on the discussion board)

• Questions on next lecture's material
  1. Write code to insert the following ints into an STL stack object, in the order given below, and then pop them all: 1, 2, 3, 4. In which order are they popped?

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Last modified: 12 Aug 2009