Python/data_structures/Stacks/__init__.py
2016-10-31 15:40:33 +09:00

24 lines
435 B
Python

class Stack:
def __init__(self):
self.stack = []
self.top = 0
def is_empty(self):
return (self.top == 0)
def push(self, item):
if self.top < len(self.stack):
self.stack[self.top] = item
else:
self.stack.append(item)
self.top += 1
def pop(self):
if self.is_empty():
return None
else:
self.top -= 1
return self.stack[self.top]