Self-test 18:
Stack and Queue

  1. What policy does stack use when inserting and removing items

    1. LILO
    2. FIFO
    3. LIFO
    Solution
    C

  2. What policy does queue use when inserting and removing items?

    1. LILO
    2. FIFO
    3. LIFO
    Solution
    B

  3. What do we say when we add an item to a stack?

    1. push
    2. add
    3. enqueue
    Solution
    A

  4. What do we say when we delete an item from a queue?

    1. pop
    2. poll
    3. dequeue
    Solution
    C

  5. What is the result of the following program?

    int main(void)
{
	int_stack s;
	int_queue q;
	int b;
	s.push(2);
	s.push(1);
	q.enqueue(2);
	q.enqueue(1);
	b = a.top();
	a.pop();
	cout << b << endl;
	b = a.top();		
	a.pop();
	cout << b << endl;
	b = q.front();		
	q.dequeue();
	cout << b << endl;
	b = q.front();		
	q.dequeue();
	cout << b << endl;
	return 0;
}
    Solution
    1
    2
    2
    1

  6. Following the example "Balanced Parentheses" in lecture notes, what are the items in the stack at the time we reach the first "[" when scanning "{ ( ( ) ( ) ( [ ] ) ) }"?

    Solution
    Answer: { ( (

  7. Fill in the blanks in the following block of code that reverse the items in an int_queue q by using a intermediate int_stack s. 

    void reverse_queue(int_queue q)
{
	int_stack s;
	while (!q.empty())
	{
		int a = q.front();		
		q.dequeue();
		s.push(a);
	}
	while (________)
	{
		______________;
		______________;
		______________;
	}
}
    Solution
    void reverse_queue(int_queue q)
{
	int_stack s;
	while (!q.empty())
	{
		int a = q.front();		
		q.dequeue();
		s.push(a);
	}
	while (!s.empty())
	{
		int a = s.top();	
		s.pop();
		q.enqueue(a);
	}
}