2.3.2 Algorithms for the main data structures

• What do algorithms and data structures do together?


  They allow data to be manipulated effectively
• What type of data structure is a stack?

  First in, last out (FILO)
• How is a stack typically implemented?

  As an array with a single pointer
• What is the purpose of the top pointer in a stack?

  It tracks the top element of the stack
• Why is the top pointer initialized at -1?

  To indicate that the stack is empty
• What does the size() function return in a stack?

  The number of elements on the stack
• How is the size of the stack calculated in pseudocode?

  Return top + 1
• What does the isEmpty() function check in a stack?

  If the top pointer is less than 0
• What does the peek() function do in a stack?

  Returns the top element without removing it
• What should be checked before using peek() on a stack?

  Whether the stack has data in it
• How is an element added to a stack?

  By updating the top pointer and inserting the element
• What happens during the pop() operation in a stack?

  The top element is removed and returned
• What must be checked before performing a pop() operation?

  That the stack isn’t empty
• What is the result of the peek() operation after pushing 1, 5, and 4 onto the stack?

  4
• What does the isEmpty() function return after pushing elements onto the stack?

  False
• What happens when trying to push onto a full stack?

  An error is returned
• What is the final output of the stack operations performed?

  4, 4, False, 2, 5
• What type of data structure is a queue?

  First in, first out (FIFO)
• How is a queue typically represented?

  As an array with two pointers
• What do the front and back pointers in a queue represent?

  Front holds the first element, back the next space
• How is the size of a queue calculated?

  By subtracting front from back
• What does the isEmpty() function check in a queue?

  If front and back point to the same position
• What does the peek() function do in a queue?

  Returns the front element without removing it
• How is an element added to a queue?

  By placing it at the back pointer's position
• What happens during the dequeue() operation in a queue?

  The front element is removed and returned
• What must be checked before performing a dequeue() operation?

  That the queue isn’t empty
• What is the result of the dequeue() operation on the queue?

  Alex
• What is the size of the queue after enqueuing Julia?

  5
• What does the peek() operation return after enqueuing Julia?

  Rajiv
• What is the final output of the queue operations performed?

  Alex, 5, Rajiv, 5, Rajiv, False
• What are the main operations associated with stacks?

  • size()
  • isEmpty()
  • peek()
  • push(element)
  • pop()
• What are the main operations associated with queues?

  • size()
  • isEmpty()
  • peek()
  • enqueue(element)
  • dequeue()
• Compare the structure and operations of stacks and queues.

  Stacks:

  • FILO structure
  • Single pointer (top)
  • Operations: push, pop, peek

  
  

  Queues:

  • FIFO structure
  • Two pointers (front, back)
  • Operations: enqueue, dequeue, peek