双端队列的实现

1. 关于双端队列
   

   dequeue.jpg
2. 实现代码

#对于双端队列，实际上相当于两个栈底部合在一起了
class Queue(object):
    """双端队列"""
    def __init__(self):
        self.__list = []

    def add_front(self, item):
        """在头部添加item"""
        self.__list.insert(0, item)

    def add_rear(self, item):
        """在尾部添加item"""
        self.__list.append(item)

    def pop_front(self):
        """从头部取出item"""
        return self.__list.pop(0)

    def pop_rear(self):
        """从尾部取出item"""
        return self.__list.pop()

    def is_empty(self):
        return self.__list == []

    def size(self):
        return len(self.__list)

if __name__ == "__main__":
    s = Queue()
    s.add_front(1)
    s.add_front(2)
    s.add_rear(3)
    s.add_rear(4)
    print(s.is_empty())
    print(s.size())
    print(s.pop_front())
    print(s.pop_rear())
    print(s.size())

/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 /Users/xinqi/PycharmProjects/test/test.py
False
4
2
4
2