def first_last_ordering_without_stack(head, reversed_head, middle):
if not _check_parameters(head, reversed_head, middle):
return
t_head = head
t_reversed_head = reversed_head
count = 1
new_head = Node()
new_head_pointer = new_head
while t_head != middle:
if count%2:
new_head.next = Node(t_head.contents)
new_head = new_head.next
# if not new_head:
# new_head = Node(t_head.contents)
# else:
# new_head.next = Node(t_head.contents)
# new_head = new_head.next
t_head = t_head.next
else:
# if not new_head:
# new_head = Node(t_reversed_head.contents)
# else:
# new_head.next = Node(t_reversed_head.contents)
# new_head = new_head.next
new_head.next = Node(t_reversed_head.contents)
new_head = new_head.next
t_reversed_head = t_reversed_head.next
count = count + 1
new_head.next = Node(t_head.contents)
return new_head_pointer
def insert_node(head, prev, node): if prev == None: temp = Node(node.contents) temp.next = head else: temp = Node(node.contents) prev.next = temp temp.next = head return temp
def _simple_list_eg(): n1 = Node(1) n2 = Node(2) n3 = Node(3) n4 = Node(4) n5 = Node(5) n1.next = n2 n2.next = n3 n3.next = n4 n4.next = n5 head = n1 return head
def _not_complete_circular_eg(): n1 = Node(1) n2 = Node(2) n3 = Node(3) n4 = Node(4) n5 = Node(5) n1.next = n2 n2.next = n3 n3.next = n4 n4.next = n5 n5.next = n2 head = n1 return head
def insert_in_front(head, diff):
# insert extra nodes of zero in the front
if head == None:
return
for i in range(diff):
temp = Node(0)
temp.next = head
head = temp
return head
def helper_insert_in_front_and_modify(node, head, prev): if not node: return node_next = node.next #insert in front temp = Node(node.contents) temp.next = head #make connection prev.next = node_next # delete node del node return temp
def insert_in_front(value, head):
temp = Node(value)
#if list is empty
if head != None:
temp.next = head
return temp