数据结构：栈 顺序表方法和单链表方法（python版）

 #!/usr/bin/env python
 # -*- coding:utf-8 -*-

 class StackUnderflow(ValueError):
     pass

 #链表节点
 class Node(object):
     def __init__(self, elem, next_ = None):
         self.elem = elem
         self.next = next_

 #顺序表实现栈
 class SStack(object):
     def __init__(self):
         self._elems = []

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

     def top(self):
         if self.is_empty():
             raise StackUnderflow
         return self._elems[-1]

     def push(self, elem):
         self._elems.append(elem)

     def pop(self):
         if self.is_empty():
             raise StackUnderflow
         return self._elems.pop()

 #链表实现栈
 class LStack(object):
     def __init__(self):
         self._top = None

     def is_empty(self):
         return self._top is None

     def top(self):
         if self.is_empty():
             raise StackUnderflow("in LStack.top()")
         return self._top.elem

     def push(self, elem):
         self._top = Node(elem, self._top)

     def pop(self):
         if self.is_empty():
             raise StackUnderflow("in LStack.pop()")
         result = self._top.elem
         self._top = self._top.next
         return result

 if __name__=="__main__":
     st1 = SStack()
     st1.push(3)
     st1.push(5)
     while not st1.is_empty():
         print(st1.pop())

     print("============")
     st2 = LStack()
     st2.push(3)
     st2.push(5)
     while not st2.is_empty():
         print(st2.pop())