def ispalindrome(linked_list):
if not linked_list.head:
return False
aux = linked_list.head
size = 0
while aux:
size += 1
aux = aux.next
if size == 1: # maybe removed
return True
i = 1
ll = None
while i <= round(size / 2):
if not ll:
ll = LinkedList(linked_list.head.value)
else:
new_head = Node(linked_list.head.value)
new_head.next = ll.head
ll.head = new_head
if size % 2 == 0 or i != round(size / 2):
linked_list.head = linked_list.head.next
i += 1
return equals(ll, linked_list)
aux = aux.next
size += 1
if kth >= size:
return
complement = size - kth
aux = linked_list.head
i = 1
while i != complement:
aux = aux.next
i += 1
return aux.value
ll = LinkedList(5)
ll.add(4)
ll.add(3)
ll.add(2)
ll.add(1)
ll_one_elem = LinkedList(1)
print(return_kth_to_last(ll, 1))
print(return_kth_to_last(ll, 2))
print(return_kth_to_last(ll, 3))
print(return_kth_to_last(ll, 4))
print(return_kth_to_last(ll, 5))
print(return_kth_to_last(ll, 6))
print(return_kth_to_last(ll_one_elem, 0))
from linked_list.likedlist import LinkedList
# Remove duplications from a linked list
# Space O(1). Time O(n²)
def remove_dup(linked_list):
first = linked_list.head
while first and first.next:
second = first
while second.next:
if first.value == second.next.value:
second.next = second.next.next
else:
second = second.next
first = first.next
ll = LinkedList(5)
ll.add(4)
ll.add(3)
ll.add(5)
ll.add(4)
ll.add(3)
print(ll)
remove_dup(ll)
print(ll)
if first_size > second_size:
while first_size != second_size:
aux1 = aux1.next
first_size -= 1
elif second_size > first_size:
while second_size != first_size:
aux2 = aux2.next
second_size -= 1
while aux1 and aux2:
if aux1 == aux2:
return aux1
aux1 = aux1.next
aux2 = aux2.next
return
first_ll = LinkedList('1')
first_ll.add('2')
first_ll.add('3')
first_ll.add('4')
first_ll.add('5')
second_ll = copy.copy(first_ll)
second_ll.head = second_ll.head.next
new_head = Node(9)
new_head.next = second_ll.head.next
second_ll.head = new_head
print(intersection(first_ll, second_ll))
val2 = aux2.value if aux2 else 0
if not aux1:
aux1_prev.next = Node((val1 + val2 + carry) % 10)
else:
aux1.value = (val1 + val2 + carry) % 10
carry = 1 if val1 + val2 + carry >= 10 else 0
aux1_prev = aux1 if aux1 else aux1_prev.next
if aux1:
aux1 = aux1.next
if aux2:
aux2 = aux2.next
return list_one
first_ll = LinkedList(1)
first_ll.add(3)
first_ll.add(5)
second_ll = LinkedList(2)
second_ll.add(4)
second_ll.add(1)
# first_ll = LinkedList(9)
# first_ll.add(5)
# first_ll.add(1)
#
# second_ll = LinkedList(7)
# second_ll.add(4)
# second_ll.add(1)
ll = None
while i <= round(size / 2):
if not ll:
ll = LinkedList(linked_list.head.value)
else:
new_head = Node(linked_list.head.value)
new_head.next = ll.head
ll.head = new_head
if size % 2 == 0 or i != round(size / 2):
linked_list.head = linked_list.head.next
i += 1
return equals(ll, linked_list)
ll = LinkedList('a')
print(ispalindrome(ll))
ll = LinkedList('a')
ll.add('a')
print(ispalindrome(ll))
ll = LinkedList('t')
ll.add('a')
ll.add('c')
ll.add('c')
ll.add('a')
ll.add('t')
print(ispalindrome(ll))
ll = LinkedList('t')
# Check is a linked lists contains a loop. Return the node at beginning of loop.
# Space O(n). Time O(n)
def loop_detect(linked_list):
if not linked_list.head:
return
dict = {}
aux = linked_list.head
while aux:
if dict.get(aux):
return aux
dict[aux] = 1
aux = aux.next
circular_ll = LinkedList('A')
circular_ll.add('B')
circular_ll.add('C')
circular_ll.add('D')
circular_ll.add('E')
tail = circular_ll.head.next.next.next.next
node_c = circular_ll.head.next.next
tail.next = node_c
print(loop_detect(circular_ll))
not_circular_ll = LinkedList('A')
not_circular_ll.add('B')
not_circular_ll.add('C')
not_circular_ll.add('D')
not_circular_ll.add('E')
print(loop_detect(not_circular_ll))