Stacks

A stack is a data structure that stores data, similar to a stack of plates in a kitchen. You can put a plate on the top of the stack, and when you need a plate, you take it from the top of the stack.

The last plate that was added to the stack will be the first to be picked up from the stack:

Figure 5.1: Example of a stack

The preceding diagram depicts a stack of plates. Adding a plate to the pile is only possible by leaving that plate on top of the pile. To remove a plate from the pile of plates means to remove the plate that is on top of the pile.

A stack is a data structure that stores the data in a specific order similar to arrays and linked lists, with several constraints:

• Data elements in a stack can only be inserted at the end (push operation)
• Data elements in a stack can only be deleted from the end (pop operation)
• Only the last data element can be read from the stack (peek operation)

A stack data structure allows...