622.py

class Node:
    def __init__(self, value):
        self.val = value
        self.next = self.pre = None
class MyCircularQueue:

    def __init__(self, k):
        self.size = k
        self.curSize = 0
        self.head = self.tail = Node(-1)
        self.head.next = self.tail
        self.tail.pre = self.head

    def enQueue(self, value):
        if self.curSize < self.size:
            node = Node(value)
            node.pre = self.tail.pre
            node.next = self.tail
            node.pre.next = node.next.pre = node
            self.curSize += 1
            return True
        return False

    def deQueue(self):
        if self.curSize > 0:
            node = self.head.next
            node.pre.next = node.next
            node.next.pre = node.pre
            self.curSize -= 1
            return True
        return False

    def Front(self):
        return self.head.next.val

    def Rear(self):
        return self.tail.pre.val

    def isEmpty(self):
        return self.curSize == 0

    def isFull(self):
        return self.curSize == self.size