栈实现(Python数据结构与算法分析)

①利用列表实现栈，将列表末尾作为栈顶

#列表尾部是栈的顶端
class Stack:
    def __init__(self):
        self.items = []

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

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

    def pop(self):
        return self.items.pop()

    def peek(self):
        return self.items[len(self.items) - 1]

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

# s =Stack()
# print(s.isEmpty())
#
# s.push(1)
# s.push('dog')
# print(s.peek())
# print(s.size())
# print(s.isEmpty())
# print(s.pop())
# print(s.size())

 ②利用列表实现栈，将列表头部作为栈顶

#列表头部是栈的顶端
class Stack:
    def __init__(self):
        self.items = []
    def isEmpty(self):
        return self.items == []
    def pop(self):
        return self.items.pop(0)
    def push(self,item):
        self.items.insert(0,item)
    def peek(self):
        return self.items[0]
    def size(self):
        return len(self.items)