queue_on_pseudo_stack.py

"""Queue represented by a pseudo stack (represented by a list with pop and append)"""
from typing import Any


class Queue:
 def __init__(self):
 self.stack = []
 self.length = 0

 def __str__(self):
 printed = "<" + str(self.stack)[1:-1] + ">"
 return printed

 """Enqueues {@code item}
 @param item
 item to enqueue"""

 def put(self, item: Any) -> None:
 self.stack.append(item)
 self.length = self.length + 1

 """Dequeues {@code item}
 @requirement: |self.length| > 0
 @return dequeued
 item that was dequeued"""

 def get(self) -> Any:
 self.rotate(1)
 dequeued = self.stack[self.length - 1]
 self.stack = self.stack[:-1]
 self.rotate(self.length - 1)
 self.length = self.length - 1
 return dequeued

 """Rotates the queue {@code rotation} times
 @param rotation
 number of times to rotate queue"""

 def rotate(self, rotation: int) -> None:
 for _ in range(rotation):
 temp = self.stack[0]
 self.stack = self.stack[1:]
 self.put(temp)
 self.length = self.length - 1

 """Reports item at the front of self
 @return item at front of self.stack"""

 def front(self) -> Any:
 front = self.get()
 self.put(front)
 self.rotate(self.length - 1)
 return front

 """Returns the length of this.stack"""

 def size(self) -> int:
 return self.length