Polish stack solution.

This commit is contained in:
Donne Martin 2016-02-20 08:11:49 -05:00
parent 08fabdf58d
commit 7a166bed67
2 changed files with 23 additions and 29 deletions

View File

@ -1,8 +1,8 @@
class Node(object):
def __init__(self, data):
def __init__(self, data, next=None):
self.data = data
self.next = None
self.next = next
class Stack(object):
@ -11,21 +11,18 @@ class Stack(object):
self.top = top
def push(self, data):
node = Node(data)
node.next = self.top
node = Node(data, self.top)
self.top = node
def pop(self):
if self.top is not None:
data = self.top.data
self.top = self.top.next
return data
return None
if self.top is None:
return None
data = self.top.data
self.top = self.top.next
return data
def peek(self):
if self.top is not None:
return self.top.data
return None
return self.top.data if self.top is not None else None
def is_empty(self):
return self.peek() is None

View File

@ -137,9 +137,9 @@
"%%writefile stack.py\n",
"class Node(object):\n",
"\n",
" def __init__(self, data):\n",
" def __init__(self, data, next=None):\n",
" self.data = data\n",
" self.next = None\n",
" self.next = next\n",
"\n",
"\n",
"class Stack(object):\n",
@ -148,21 +148,18 @@
" self.top = top\n",
"\n",
" def push(self, data):\n",
" node = Node(data)\n",
" node.next = self.top\n",
" node = Node(data, self.top)\n",
" self.top = node\n",
"\n",
" def pop(self):\n",
" if self.top is not None:\n",
" data = self.top.data\n",
" self.top = self.top.next\n",
" return data\n",
" return None\n",
" if self.top is None:\n",
" return None\n",
" data = self.top.data\n",
" self.top = self.top.next\n",
" return data\n",
"\n",
" def peek(self):\n",
" if self.top is not None:\n",
" return self.top.data\n",
" return None\n",
" return self.top.data if self.top is not None else None\n",
"\n",
" def is_empty(self):\n",
" return self.peek() is None"
@ -308,21 +305,21 @@
],
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"name": "python3"
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"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
"version": 3
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"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
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