数据结构与算法 栈与队列

栈，遵循后入先出原则，即后进栈的元素先出栈。其代码实现如下：

class stack(object):
    """栈"""

    def __init__(self):
        self.items = []

    def is_empty(self):#判断是否为空栈
        return self.items == []

    def push(self, item):#入栈
        self.items.append(item)

    def pop(self):#出栈
        return print(self.items.pop())

    def peak(self):#取栈顶元素
        return self.items[len(self.items) - 1]

    def size(self):#栈的大小
        return len(self.items)

    def travel(self):#遍历栈
        for i in self.items:
            print(i, end=" ")
          

#测试
if __name__ == "__main__":
    s = stack()
    s.push('I')
    s.push('am')
    s.push('ironman')
    s.travel()
    s.pop()
    s.pop()
    s.pop()

队列遵循后入后出的原则，其代码实现如下：

class Sequence(object):
    def __init__(self):
        self.items = []

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

    def inSequence(self, item):
        self.items.insert(0, item)

    def outSequence(self):
        print(self.items.pop())

    def sizeofSequence(self):
        print(len(self.items))
    def travel(self):
        for i in self.items:
            print(i,end=" ")
if __name__=="__main__":
    s=Sequence()
    s.inSequence('I')
    s.inSequence('am')
    s.inSequence('Ironman')
    s.travel()
    s.outSequence()
    s.sizeofSequence()