Learn More Python 3 the Hard Way: The Next Step for New Python Programmers

Exercise 15. Stacks and Queues

When working with data structures you’ll oftentimes encounter a structure that is similar to another. A Stack is similar to a SingleLinkedList from Exercise 13, and a Queue is similar to a DoubleLinkedList from Exercise 14. The only difference is a Stack and a Queue restrict the possible operations to simplify how they are used. This helps reduce defects since you can’t accidentally use the Stack like a Queue and cause problems. In a Stack, the nodes are “pushed” onto the “top” and then “popped” from the top as well. With a Queue, the nodes are shifted to the “tail” and then unshifted off the “head” of the structure. Both of these operations are simply simplifications of the SingleLinkedList and DoubleLinkedList ...