STACKS AND QUEUES



 1. (Sedgewick, Exercise 4.6).  A letter means push and an asterisk means pop in the
    following sequence.  Give the sequence of values returned by the pop operations
    when this sequence of operations is performed on an initially empty LIFO stack.

         E A S * Y * Q U E * * * S T * * * I O * N * * *

 2. (Sedgewick, Exercise 4.18). A letter means push and an asterisk means pop in the
    following sequence.  Give the contents of s[0], ..., s[4] after the execution of
    Sedgewick Program 4.4 (or the array implementation of a stack in the
    ADT Lecture).

         L A * S T I * N * F I R * S T * * O U * T * * * * * * 

 3. Modify the stack program in the lecture notes to issue a warning and exit if
    the client program attempt to pop an empty stack or push onto a full one.

 4. (Sedgewick, Exercise 4.31).  A letter means put and an asterisk means get in the 
    following sequence.  Give the sequence of values returned by the get operation
    when this sequence of operations is performed on an initially empty FIFO queue.

         E A S * Y * Q U E * * * S T * * * I O * N * * *

 5. (Sedgewick, Exercise 4.30).  Give the contens of q[0], ..., q[4] after the
    execution of the operations illustrated in Figure 4.6 using Program 4.11. Assume
    maxN is 10, as in Fig. 4.8.


 6. Suppose that an intermixed sequence of push and pop operations are performed.
    The pushes push the integers 0 through 9 in order; the pops print out the return
    value. Which of the following sequences could not occur?

       (a)  4 3 2 1 0 9 8 7 6 5
       (b)  4 6 8 7 5 3 2 9 0 1 
       (c)  2 5 6 7 4 8 9 3 1 0
       (d)  4 3 2 1 0 5 6 7 8 9

 7. Write a program that reads in a sequence of characters and prints them
    in reverse order.  Use a stack.

 8. Write a program that reads in a sequence of characters, and determines whether
    its parentheses, braces, and curly braces are "balanced."  Hint:  for left
    delimiters, push onto stack; for right delimiters, pop from stack and check
    whether popped element matches right delimiter.

 9. Write a program that reads in a positive integer and prints the binary
    representation of that integer.  Hint:  divide the integer by 2.

10. Add an interface function void STACKmultipop(int k) that pops k elements from
    the stack, or until the stack is empty.

11. (*) Show how to implement a queue using two stacks.