def add_two_numbers(head1: Optional[ListNode],
head2: Optional[ListNode]) -> Optional[ListNode]:
node1 = head1
node2 = head2
dummy_node = ListNode(0)
result = dummy_node
carry = 0
while node1 or node2:
val1 = 0
val2 = 0
if node1:
val1 = node1.val
node1 = node1.next
if node2:
val2 = node2.val
node2 = node2.next
total = val1 + val2 + carry
carry = int(total / 10)
result.next = ListNode(total % 10)
result = result.next
if carry > 0:
result.next = ListNode(carry)
return dummy_node.next
def test_is_palindrome():
head = ListNode(1)
assert is_palindrome(head)
head.next = ListNode(2)
assert not is_palindrome(head)
head.next.next = ListNode(1)
assert is_palindrome(head)
def test_merge_two_lists():
list1 = ListNode(1)
assert get_list_values(merge_two_lists(list1, None)) == [1]
list2 = ListNode(1)
assert get_list_values(merge_two_lists(list1, list2)) == [1, 1]
list1.next = ListNode(2)
list1.next.next = ListNode(4)
list2.next = ListNode(3)
list2.next.next = ListNode(4)
assert get_list_values(merge_two_lists(list1, list2)) == [1, 1, 2, 3, 4, 4]
def test_1():
head = Node(0)
head.next = Node(1)
head.next.next = Node(2)
head.next.next.next = Node(3)
head.next.next.next.next = Node(4)
head.next.next.next.next.next = Node(5)
head.next.next.next.next.next.next = Node(6)
head.next.next.next.next.next.next.next = Node(7)
head.next.next.next.next.next.next.next.next = Node(8)
head.next.next.next.next.next.next.next.next.next = Node(9)
head.next.next.next.next.next.next.next.next.next.next = head.next.next.next.next
assert findLoop(head) == head.next.next.next.next
def test_detect_cycle_with_set():
assert detect_cycle_with_set(ListNode(1)) is None
head = ListNode(1)
head.next = head
assert detect_cycle_with_set(head) == head
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = head.next
assert detect_cycle_with_set(head) == head.next
def create_linked_list(values: List[int]) -> Optional[ListNode]:
"""
Create linked list from values list
:param values: the values list of linked list
:type values: list of int
:return: head node of linked list
:rtype: ListNode or None
"""
if not values:
return None
head = ListNode(values[0])
cur_node = head
for val in values[1:]:
cur_node.next = ListNode(val)
cur_node = cur_node.next
return head
def reverse_linked_list_recursive(head: ListNode) -> Optional[ListNode]:
if not head or not head.next:
return head
new_head = reverse_linked_list_recursive(head.next)
head.next.next = head
head.next = None
return new_head
def test_remove_elements():
assert remove_elements(None, 1) is None
head = ListNode(1)
assert remove_elements(head, 1) is None
assert remove_elements(head, 2) is head
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(2)
head.next.next.next = ListNode(3)
assert get_list_values(remove_elements(head, 2)) == [1, 3]
def test_odd_even_linked_list():
head = ListNode(1)
assert odd_even_list(head) == head
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = ListNode(5)
assert get_list_values(odd_even_list(head)) == [1, 3, 5, 2, 4]
def test_insert():
head = None
assert get_cyclic_list_values(insert(head, 1)) == [1]
head = ListNode(1)
head.next = head
assert get_cyclic_list_values(insert(head, 2)) == [1, 2]
head = ListNode(3)
head.next = ListNode(4)
head.next.next = ListNode(1)
head.next.next.next = head
assert get_cyclic_list_values(insert(head, 2)) == [3, 4, 1, 2]
def remove_elements(head: Optional[ListNode], val: int) -> Optional[ListNode]:
dummy_node: ListNode = ListNode(0)
dummy_node.next = head
previous: ListNode = dummy_node
current: Optional[ListNode] = head
while current:
if current.val == val:
previous.next = current.next
current = current.next
else:
previous = current
current = current.next
return dummy_node.next
def remove_nth_from_end(head: ListNode, nth: int) -> Optional[ListNode]:
dummy: ListNode = ListNode(0)
dummy.next = head
previous: ListNode = dummy
lead: ListNode = dummy
# Move lead forward
for _ in range(nth + 1):
lead = lead.next
# Move through list until lead is None
while lead:
previous = previous.next
lead = lead.next
# Delete Node by relinking nodes or reassigning head
previous.next = previous.next.next
return dummy.next
def test_find_middle_node():
head = ListNode(1)
assert find_middle_node(head) == head
head.next = ListNode(2)
assert find_middle_node(head) == head
# 1, 2, 3
head.next.next = ListNode(3)
assert find_middle_node(head) == head.next
head.next.next.next = ListNode(4)
assert find_middle_node(head) == head.next
def merge_two_lists(head1: Optional[ListNode], head2: Optional[ListNode]) -> Optional[ListNode]:
if not head1 and not head2:
return None
node1 = head1
node2 = head2
dummy_node = ListNode(0)
current_node = dummy_node
while node1 and node2:
if node1.val <= node2.val:
current_node.next = node1
node1 = node1.next
else:
current_node.next = node2
node2 = node2.next
current_node = current_node.next
if node1:
current_node.next = node1
if node2:
current_node.next = node2
return dummy_node.next
def test_add_two_numbers():
head1 = ListNode(1)
head1.next = ListNode(2)
head1.next.next = ListNode(3)
head2 = None
assert get_list_values(add_two_numbers(head1, head2)) == [1, 2, 3]
head1 = ListNode(5)
head2 = ListNode(5)
assert get_list_values(add_two_numbers(head1, head2)) == [0, 1]
head1.next = ListNode(2)
head2.next = ListNode(3)
head2.next.next = ListNode(4)
assert get_list_values(add_two_numbers(head1, head2)) == [0, 6, 4]
def test_detect_cycle():
assert detect_cycle(ListNode(1)) is None
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
assert detect_cycle(head) is None
head = ListNode(1)
head.next = head
assert detect_cycle(head) == head
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = head.next
assert detect_cycle(head) is head.next
def test_get_intersection_node():
head1 = ListNode(1)
head1.next = ListNode(2)
head2 = ListNode(1)
head2.next = ListNode(2)
head2.next.next = ListNode(3)
assert get_intersection_node_with_set(head1, head2) is None
head1 = ListNode(1)
head2 = head1
assert get_intersection_node_with_set(head1, head2) is head1
head1 = ListNode(1)
head1.next = ListNode(2)
head1.next.next = ListNode(3)
head1.next.next.next = ListNode(4)
head2 = ListNode(1)
head2.next = head1.next.next
assert get_intersection_node_with_set(head1, head2) is head1.next.next
def insert(head: Optional[ListNode], value: int) -> Optional[ListNode]:
if not head:
cyclic_list = ListNode(value)
cyclic_list.next = cyclic_list
return cyclic_list
previous = head
node = head.next
while node:
if previous.val <= value <= node.val:
new_node = ListNode(value)
previous.next = new_node
new_node.next = node
return head
if previous.val > node.val:
if value >= previous.val or value <= node.val:
new_node = ListNode(value)
previous.next = new_node
new_node.next = node
return head
previous = node
node = node.next
if previous == head:
break
new_node = ListNode(value)
previous.next = new_node
new_node.next = node
return head
def test_remove_nth_from_end():
head = ListNode(1)
assert remove_nth_from_end(head, 1) is None
head = ListNode(1)
head.next = ListNode(2)
assert remove_nth_from_end(head, 2).val == 2
assert remove_nth_from_end(head, 1).val == 1
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
assert remove_nth_from_end(head, 2).next.next.val == 4
def test_rotate_list():
head = None
assert rotate_list(head, 1) is None
head = ListNode(1)
assert get_list_values(rotate_list(head, 1)) == [1]
assert get_list_values(rotate_list(head, 3)) == [1]
head.next = ListNode(2)
assert get_list_values(rotate_list(head, 1)) == [2, 1]
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = ListNode(5)
assert get_list_values(rotate_list(head, 2)) == [4, 5, 1, 2, 3]
def test_reverse_linked_list():
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
assert get_list_values(reverse_linked_list_recursive(head)) == [3, 2, 1]
head = ListNode(1)
head.next = ListNode(2)
assert get_list_values(reverse_linked_list_recursive(head)) == [2, 1]
head = ListNode(1)
assert get_list_values(reverse_linked_list_recursive(head)) == [1]