Python/data_structures/Queue/QueueOnPseudoStack.py
2017-10-25 01:37:11 +05:30

51 lines
1.4 KiB
Python

"""Queue represented by a pseudo stack (represented by a list with pop and append)"""
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):
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):
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):
for i 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):
front = self.get()
self.put(front)
self.rotate(self.length-1)
return front
"""Returns the length of this.stack"""
def size(self):
return self.length