class LinkedList(object): class _StackNode(object): def __init__(self, item=None, link=None): self.item = item self.link = link def get_item(self): return self.item def get_next(self): return self.link def set_next(self, new_next): self.link = new_next def __init__(self, head=None): self.head = head def insert(self, item): new_node = Node(item) new_node.set_next(self.head) self.head = new_node def __len__(self): current = self.head count = 0 while current: count += 1 current = current.get_next() return count def peek(self): current_node = self.head while current_node is not None: print current_node.item, \" -> \", current_node = current_node.next print None def pop(self, node_value): current_node = self.head previous_node = None while current_node is not None: if current_node.item == node_value: # if this is the first node (head) if previous_node is not None: previous_node.next = current_node.next else: self.head = current_node.next previous_node = current_node current_node = current_node.next def push(self, item): node = Node(item, None) if self.head is None: self.head = self.tail = node else: self.tail.next = node self.tail = node Solution class LinkedList(object): class _StackNode(object): def __init__(self, item=None, link=None): self.item = item self.link = link def get_item(self): return self.item def get_next(self): return self.link def set_next(self, new_next): self.link = new_next def __init__(self, head=None): self.head = head def insert(self, item): new_node = Node(item) new_node.set_next(self.head) self.head = new_node def __len__(self): current = self.head count = 0 while current: count += 1 current = current.get_next() return count def peek(self): current_node = self.head while current_node is not None: print current_node.item, \" -> \", current_node = current_node.next print None def pop(self, node_value): current_node = self.head previous_node = None while current_node is not None: if current_node.item == node_value: # if this is the first node (head) if previous_node is not None: previous_node.next = current_node.next else: self.head = current_node.next previous_node = current_node current_node = current_node.next def push(self, item): node = Node(item, None) if self.head is None: self.head = self.tail = node else: self.tail.next = node self.tail = node.

1. class LinkedList(object):
class _StackNode(object):
def __init__(self, item=None, link=None):
self.item = item
self.link = link
def get_item(self):
return self.item
def get_next(self):
return self.link
def set_next(self, new_next):
self.link = new_next
def __init__(self, head=None):
self.head = head
def insert(self, item):
new_node = Node(item)
new_node.set_next(self.head)
self.head = new_node
def __len__(self):
current = self.head
count = 0
while current:
count += 1
current = current.get_next()
return count

2. def peek(self):
current_node = self.head
while current_node is not None:
print current_node.item, " -> ",
current_node = current_node.next
print None
def pop(self, node_value):
current_node = self.head
previous_node = None
while current_node is not None:
if current_node.item == node_value:
# if this is the first node (head)
if previous_node is not None:
previous_node.next = current_node.next
else:
self.head = current_node.next
previous_node = current_node
current_node = current_node.next
def push(self, item):
node = Node(item, None)
if self.head is None:
self.head = self.tail = node
else:
self.tail.next = node
self.tail = node
Solution
class LinkedList(object):
class _StackNode(object):

3. def __init__(self, item=None, link=None):
self.item = item
self.link = link
def get_item(self):
return self.item
def get_next(self):
return self.link
def set_next(self, new_next):
self.link = new_next
def __init__(self, head=None):
self.head = head
def insert(self, item):
new_node = Node(item)
new_node.set_next(self.head)
self.head = new_node
def __len__(self):
current = self.head
count = 0
while current:
count += 1
current = current.get_next()
return count
def peek(self):
current_node = self.head
while current_node is not None:
print current_node.item, " -> ",
current_node = current_node.next
print None

4. def pop(self, node_value):
current_node = self.head
previous_node = None
while current_node is not None:
if current_node.item == node_value:
# if this is the first node (head)
if previous_node is not None:
previous_node.next = current_node.next
else:
self.head = current_node.next
previous_node = current_node
current_node = current_node.next
def push(self, item):
node = Node(item, None)
if self.head is None:
self.head = self.tail = node
else:
self.tail.next = node
self.tail = node