Lecture 11

Learning objectives

After this class, you should be able to:

1. Given certain operations on a deque, 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.

Reading assignment

1. Section 3.8 (up to fig 3.27), class notes for deque implementation (do not use the one in the book).
2. Page 137 and 138.

Exercises and review questions

• Exercises and review questions on current lecture's material
  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)

• Questions on next lecture's material
  1. Assume that we perform the following operation on the rightmost figure in Fig. 4.1 (page 138): push(8); pop(); pop();. Draw the state of the stack on the conclusion of the above operations.

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Last modified: 12 Feb 2008