circular queue.py

# PYTHON PROGRAM TO CREATE A CIRCULAR QUEUE

classQueue:
def__init__(self,maxsize):
self.items=maxsize*[None]
self.maxsize=maxsize
self.start=-1
self.top=-1

def__str__(self):
values=[str(x) forxinself.items]
return' '.join(values)



# to check if queue is full
defisFull(self):
ifself.top+1==self.start:
returnTrue
elifself.start==0andself.top+1==self.maxsize:
returnTrue
else:
returnFalse



# to check if queue is empty
defisEmpty(self):
ifself.top==-1:
returnTrue
else:
returnFalse



# insert elements
defEnqueue(self,value):
ifself.isFull():
return"queue is full"
else:
ifself.top+1==self.maxsize:
self.top=0
else:
self.top+=1
ifself.start==-1:
self.start=0
self.items[self.top]=value
return"element inserted"



defdequeue(self):
ifself.isEmpty():
return"there is no element in queue"
else:
firstElement=self.items[self.start]
start=self.start
ifself.start==self.top:
self.start=-1
self.top=-1
elifself.start+1==self.maxsize:
self.start=0
else:
self.start+=1
self.items[start]=None
returnfirstElement



# peek()
defpeek(self):
ifself.isEmpty():
return"no element in queue"
else:
returnself.items[self.start]



#delete entire queue
defdelete(self):
self.items=self.maxsize*[None]
self.top=-1
self.start=-1