| 4 | self.next = None |
| 5 | |
| 6 | class Stack: |
| 7 | # 初始化空栈 |
| 8 | def __init__(self): |
| 9 | self.top = None |
| 10 | |
| 11 | # 判断栈是否为空 |
| 12 | def is_empty(self): |
| 13 | return self.top == None |
| 14 | |
| 15 | # 入栈操作 |
| 16 | def push(self, value): |
| 17 | cur = Node(value) |
| 18 | cur.next = self.top |
| 19 | self.top = cur |
| 20 | |
| 21 | # 出栈操作 |
| 22 | def pop(self): |
| 23 | if self.is_empty(): |
| 24 | raise Exception('Stack is empty') |
| 25 | else: |
| 26 | cur = self.top |
| 27 | self.top = self.top.next |
| 28 | del cur |
| 29 | |
| 30 | # 获取栈顶元素 |
| 31 | def peek(self): |
| 32 | if self.is_empty(): |
| 33 | raise Exception('Stack is empty') |
| 34 | else: |
| 35 | return self.top.value |
| 36 | |
| 37 | |
| 38 | stack = Stack() |