Python Data Structures and Algorithms

Stack-based queue

Yet another implementation of a queue is to use two stacks. Once more, the Python list class will be used to simulate a stack:

class Queue:     def __init__(self):         self.inbound_stack = []         self.outbound_stack = [] 

The preceding queue class sets the two instance variables to empty lists upon initialization. These are the stacks that will help us implement a queue. The stacks in this case are simply Python lists that allow us to call push and pop methods on them.

The inbound_stack is only used to store elements that are added to the queue. No other operation can be performed on this stack.