#19 Stacks Queues and Linked Lists

1. Which properties do lists have?

• A. Static and immutable
• B. tatic and mutable
• C. Dynamic and immutable
• D. Dynamic and mutable

2. Which property do stacks have?

• A. LILO
• B. FIFO
• C. FOFI
• D. LIFO

3. Which property do queues have?

• A. Items get enqueued and later dequeued
• B. Items get dequeued and later enqueued
• C. Items get pushed and later popped
• D. Items get popped and later pushed

4. A stack is implemented using an array in a procedural programming language where the array uses zero-based indexing. The stack pointer always points to the top of the stack. Identify the statement which is false.

• A. When the stack is empty the stack pointer can be set to -1
• B. When an item is pushed to the stack, the data value is written to the element pointed to by the stack pointer, then the stack pointer is incremented
• C. When the stack is full, the integer value of the stack pointer will be 1 less than the length of the array
• D. When popping a value from the stack, it is important to firstly check the value of the stack pointer to ensure that the stack is not empty

5. A queue is implemented using an array of strings in a procedural programming language where the array uses zero-based indexing. The length of the array is set to 2000 and all elements are set to null values before strings start to get enqueued and dequeued. The program works left to right through the array. Which of the following statements is false?

• A. Unless the programmer develops an algorithm based on the concept of a circular queue, the front of the queue will never be found to the right of the back of the queue in the array
• B. After some strings have been enqueued, on the first occasion where a string is dequeued it will definitely be from array index 0
• C. Since this is a queue of strings, no pointer is needed for the back of the queue because it will simply be a case of locating the first null pointer and this will reveal where the queue ends
• D. The programmer has the option of either nudging all values to the left each time a value is dequeued (so index 0 is always the front of a non- empty queue), or just allow the queue to have its front and back indicated by two pointers (integer variables)

6. Study the following array of characters being used to implement a queue. Which of the operations below are impossible?

• A. Enqueue 'j' and 'm' and then dequeue 'z'
• B. Enqueue 'c' and dequeue 'z' then 'p'
• C. Dequeue 'w' then enqueue 's', 'v' and 'q
• D. Dequeue 'z' then enqueue 'y' and 's'

7. Study the following array of integers being used to implement a queue. Which of the statements below is true?

• A. There are six items in the queue
• B. The queue has to be sorted before it can be of use
• C. The only value that can be dequeued is 88
• D. The value 81 joined the queue the most recently

8. What validation must take place before an item can be dequeued?

• A. Is the queue empty?
• B. Is the queue full?
• C. Is the queue an array?
• D. What data type is stored in the queue?

9. The history of a queue's changes over time is shown below. In this case, the programmer chose to fit all items tightly to the left of the array every time an element was dequeued. It has been implemented as an array of strings. Which of the following is not a correct sequence of steps that occurred when managing the queue shown?

• A. Dequeue(), enqueue(kestrel), dequeue()
• B. Enqueue(owl), dequeue(), dequeue()
• C. Enqueue(robin), dequeue(), enqueue(kestrel)
• D. Enqueue(hawk), dequeue(), enqueue(robin)

10. Which statement best describes the nature of the relationship between the data structures given?

• A. A queue is a reversed stack
• B. Stacks and queues are essentially just lists with additional rules applied
• C. Queues can be converted into lists by pushing their items to a stack
• D. Stacks and lists are both different from queues because a queue has the additional rule that values cannot be added in the middle