py循环队列

循环队列

class CircularQueue():
	def __init__(self, size=1):
		self.size = size
		self.data = [None for i in range(size)] 
		self.front = self.rear = -1

	def put(self, data):
		if ((self.rear + self.front + 1) >= self.size
			or self.front > self.rear):
            # condition if queue is full
			# print('333')
			self.data[self.rear] = data
			self.front = (self.front + 1) % self.size
			self.rear = (self.rear + 1) % self.size
		elif (self.front == self.rear):
            # condition for empty queue
			# print('111')
			self.front = 0
			self.data[self.front] = data
			self.rear = (self.front + 1) % self.size
		else:			
			# next position of rear
			# print('222')
			self.data[self.rear] = data
			self.rear = (self.rear + 1) % self.size

	def empty(self):
		if (self.front == -1):
			return True
		return False
			
	def get(self):
		if self.empty():
			return None
		rtn = self.data[self.front]
		self.data[self.front] = None
		if (self.front != self.rear):
			self.front = (self.front + 1) % self.size
		else:
			self.front = self.rear = -1
		return rtn

	def display(self):
		print(self.data, self.front, self.rear)

if __name__ == '__main__':
    ob = CircularQueue(5)
    for i in range(12):
        ob.put(i)
        ob.display()
    print('---------------------')
    for i in range(12):
        print(ob.get())
        ob.display()