class SingleLinkedStack0:
def __init__(self):
self.items = SingleLinkedList()
self.length = 0
def push(self, item):
self.items.append(item)
self.length += 1
return True
def pop(self):
if len(self.items) == 0:
return None
return self.items.pop(self.length - 1)
def __len__(self):
return len(self.items)
def __repr__(self):
"""
显示栈的容量
"""
return "<SingleLinkedStack0: %d>" % self.length
