def sll_swap_node(sll: Singlellist, x, y) -> None:
if x == y:
return
# S1: find prev_x, curr_x
ptr = sll.head
while ptr.next.value != x:
ptr = ptr.next
prev_x = ptr
curr_x = ptr.next
# S1: find prev_y, curr_y
ptr = sll.head
while ptr.next.value != y:
ptr = ptr.next
prev_y = ptr
curr_y = ptr.next
# S2: change prev
if prev_x is None: # x is the head
sll.head = curr_y
else:
prev_x.next = curr_y
if prev_y is None: # y is the head
sll.head = curr_x
else:
prev_y.next = curr_x
# S3: change next
temp = curr_x.next
curr_x.next = curr_y.next
curr_y.next = temp
def concatenating_linked_lists(
l1: Singlellist,
l2: Singlellist,
) -> Singlellist:
result = Singlellist()
result.head = l1.head
l1.tail.next = l2.head
return result
def reverse_sll_loop(sll: Singlellist) -> Singlellist:
if len(sll) == 1:
return sll
head = sll.head
prev_node = None
curr_node = sll.head
while curr_node is not None:
next_node = curr_node.next
curr_node.next = prev_node
prev_node = curr_node
curr_node = next_node
sll.head = sll.tail
sll.tail = head