使用链表实现堆栈的Python程序

当需要使用链表实现堆栈数据结构时，需要定义一个向链表添加（压入值）元素的方法，以及一个删除（弹出值）链表元素的方法。

下面是一个示例−

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例子

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class Stack_structure:
    def __init__(self):
        self.head = None

    def push_val(self, data):
        if self.head is None:
            self.head = Node(data)
        else:
            newNode = Node(data)
            newNode.next = self.head
            self.head = newNode

    def pop_val(self):
        if self.head is None:
            return None
        else:
            del_Val = self.head.data
            self.head = self.head.next
            return del_Val

my_instance = Stack_structure()
while True:
    print('push <value>')
    print('pop')
    print('quit')
    my_input = input('What action would you like to perform ? ').split()

    operation = my_input[0].strip().lower()
    if operation == 'push':
        my_instance.push_val(int(my_input[1]))
    elif operation == 'pop':
        del_Val = my_instance.pop_val()
        if del_Val is None:
            print('The stack is empty.')
        else:
            print('The deleted value is : ', int(del_Val))
    elif operation == 'quit':
        break

输出

push <value>
pop
quit
你想执行哪个操作？push 56
push <value>
pop
quit
你想执行哪个操作？push 78
push <value>
pop
quit
你想执行哪个操作？push 90
push <value>
pop
quit
你想执行哪个操作？pop
删除的值是: 90
push <value>
pop
quit
你想执行哪个操作？quit