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Copy pathCircularQueue.py
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62 lines (53 loc) · 1.75 KB
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class CircularQueue(object):
def __init__(self, size):
"""
Initializing CircularQueue
"""
self.size = size
self._front = -1
self._rear = -1
self.queue = [None] * size
def front(self):
"""
Return the value at the front of the queue
"""
return self.queue[self._front]
def rear(self):
"""
Return the value at the rear of the queue
"""
return self.queue[self._rear]
def enqueue(self, value):
"""
Insert value into the rear of the circular queue
"""
if (self._rear == self.size - 1 and self._front == 0) or (self._rear == self._front-1):
# Queue is full
raise OverflowError("CircularQueue is full")
elif (self._rear == -1):
# Setting up for first item
self._rear = 0
self._front = 0
else:
# Calculating rear index after insert
self._rear = (self._rear + 1) % self.size
self.queue[self._rear] = value
def dequeue(self):
"""
Remove and return the value at the front of the circular queue
"""
if(self._front==-1):
# Queue is empty
raise IndexError("CircularQueue is empty")
elif(self._front == self._rear):
# Remove the last remaning value and indicate the queue empty
value = self.queue[self._front]
self._front = -1
self._rear = -1
return value
else:
# Return the value at the front of the queue
value = self.queue[self._front]
self.queue[self._front] = None
self._front = (self._front + 1 ) % self.size
return value