Description

Stacks and Queues

(independent simply means that the method works right no matter what class it is in).

Exercise 1

Write an independent method public long removeSecond (StackX stack): It removes and

returns the element just below the top element if the stack has at least two elements, otherwise it

simply returns null without modifying the stack.

Exercise 3 (harder)

Write an independent method

public static void removeDownTo (StackX stack, long ob): It pops all values off the

stack down to but not including the first element it sees that is equal to the second parameter. If

none are equal, leave the stack empty.

Exercise 4 (harder)

Write an independent method public static Object removeSecond (Queue queue): It

removes and returns the element just behind the front element. Precondition: The queue has at

least two elements. Hint: Create a new object totally different from any that could possibly be on the

queue.

Exercise 5*

Write an independent method

public static void transfer (StackX one, StackX two): It transfers all elements in

the first parameter onto the top of the second parameter, keeping the same order. So what was

initially on top of one ends up on top of two . Hint: Use a third stack temporarily.

Exercise 6*

Write an independent method public static void reverse (Queue queue): It reverses the

order of the elements on the queue.

Exercise 7**

Write an independent method

public static void removeBelow (Queue queue, long ob): It removes all values from

the queue that come after the first element it sees that is equal to the second parameter. If none are

equal, leave the queue as it was originally.

Exercise 8**

Write an independent method named

interchange(StackX one, StackX two): You have two StackX parameters. All the items on

each stack are to end up on the other stack in the same order, so that each stack has the items

that the other stack had at the beginning. Use only one additional temporary stack.

Exercise 10 (harder)

Add a method public boolean equals (long ob)to the StackX class: The executor tells

whether ob is an StackX whose elements are equal to its own in the same order.

Exercise 11*

Add a method public int search (long ob)to the StackX class: The executor tells how many

elements would have to be popped to have ob removed from the stack; it returns -1 if ob is not in

the stack.

Exercise 14.14

Add a method public String toString() to the Queue class: The executor returns the

concatenation of the string representation of all elements currently in the queue with a tab character

before each element, in order from front to rear. This is very useful for debugging purposes.

Exercise 14.15 (harder)

Write a method public void removeAfter (long ob)

that could be added to Queue: The executor removes all values from the queue that come after the

element closest to the rear that is equal to the parameter. If none are equal, leave the queue as it

was originally. Handle ob == null correctly.

Exercise 14.16*

Add a method public boolean equals (long ob) to the Queue class: The executor tells

whether ob is an Queue with whose elements are equal to its own in the same order. Do not throw

any Exceptions.

Exercise 14.17*

Add a method public void clear() to the Queue class: The executor deletes all the elements

it contains, thereby becoming empty.