class Node():
def __init__(self, value, next_node=None):
self.value = value
self.next_node = next_node
class LinkedList():
def __init__(self, value_first_item):
self.head = Node(value_first_item)
self.length = 1
self.tail = self.head
def get_head(self):
return self.head.value
def get_tail(self):
return self.tail.value
def append(self, value):
new_node = Node(value)
self.tail.next_node = new_node
self.tail = new_node
self.length+=1
def prepend(self, value):
new_node = Node(value, self.head)
self.head = new_node
self.length+=1
def get_position(self, position):
""" get the value of a specific position in the linked list."""
if position < 0:
raise IndexError("No negative positions")
elif position > self.length:
raise IndexError("Position out of boundaries")
elif position == self.length:
return self.get_tail()
elif position == 0:
return self.get_head()
node = self.head.next_node
curr_position = 1
if node != None:
if position == 1:
return node.value
else:
while node.next_node != None: # traversing
node = node.next_node
curr_position+=1
if curr_position == position:
break
return node.value
def insert(self, value, position):
""" Insert a new node in the middle of the list"""
if position < 0:
raise IndexError("No negative positions")
elif position > self.length:
raise IndexError("Position out of boundaries")
new_node = Node(value)
curr_node = self.head
curr_position = 0
while curr_node.next_node != None:
curr_node = self.head.next_node
curr_position += 1
if curr_position == position-1:
new_node = Node(value, curr_node.next_node)
curr_node.next_node = new_node
break
pass
def printLinkedList(self):
curr_node = self.head
curr_position = 0
print(f"{curr_position}: {curr_node.value}")
while curr_node.next_node != None:
curr_node = curr_node.next_node
curr_position+=1
print(f"{curr_position}: {curr_node.value}")
print("Hello World!")
myLinkedList = LinkedList(5)
print(myLinkedList.get_head())
print(myLinkedList.get_tail())
myLinkedList.append(10)
myLinkedList.append(15)
print(myLinkedList.get_head())
assert(myLinkedList.get_head() == 5)
assert(myLinkedList.get_tail() == 15)
print(myLinkedList.get_position(1))
myLinkedList.append(20)
print(myLinkedList.get_position(3))
print(myLinkedList.get_position(4))
assert(myLinkedList.get_position(4) == 20)
myLinkedList.prepend(2)
assert(myLinkedList.get_head() == 2)
assert(myLinkedList.get_position(0) == 2)
myLinkedList.insert(value=7,position=2)
assert(myLinkedList.get_position(2)==7)
myLinkedList.printLinkedList()
print("Good-bye Cruel World")
