def test_1(self):
l4 = ListNode(5)
l3 = ListNode(4)
l3.next = l4
l2 = ListNode(3)
l2.next = l3
l1 = ListNode(2)
l1.next = l2
l0 = ListNode(1)
l0.next = l1
new_l = remove_nth_from_end(l0, 2)
str_new_l = stringify_list(new_l)
self.assertEqual(str_new_l, '1 -> 2 -> 3 -> 5')
def test_1(self):
l1_2 = ListNode(4)
l1_1 = ListNode(2)
l1_1.next = l1_2
l1_0 = ListNode(1)
l1_0.next = l1_1
l2_2 = ListNode(4)
l2_1 = ListNode(3)
l2_1.next = l2_2
l2_0 = ListNode(1)
l2_0.next = l2_1
expected = '1 -> 1 -> 2 -> 3 -> 4 -> 4'
merged = merge_two_lists(l1_0, l2_0)
self.assertEqual(stringify_list(merged), expected)
def test_1(self):
# Build list 1
l1_2 = ListNode(3)
l1_1 = ListNode(4)
l1_1.next = l1_2
l1_0 = ListNode(2)
l1_0.next = l1_1
# Build list 2
l2_2 = ListNode(4)
l2_1 = ListNode(6)
l2_1.next = l2_2
l2_0 = ListNode(5)
l2_0.next = l2_1
sum_list_node_0 = add_two_numbers(l1_0, l2_0)
self.assertEqual(stringify_list(sum_list_node_0), '7 -> 0 -> 8')
def test_4(self):
l7_0 = ListNode(9)
l7_1 = ListNode(9)
l7_0.next = l7_1
l8_0 = ListNode(1)
sum_list_node_0 = add_two_numbers(l7_0, l8_0)
self.assertEqual(stringify_list(sum_list_node_0), '0 -> 0 -> 1')
def test_2(self):
l1 = ListNode(2)
l0 = ListNode(1)
l0.next = l1
new_l = remove_nth_from_end(l0, 2)
str_new_l = stringify_list(new_l)
self.assertEqual(str_new_l, '2')
def reverse(head: ListNode) -> ListNode:
if not head or not head.next:
return head
prev = head
head = head.next
prev.next = None
while head:
nxt = head.nxt
head.next = prev
prev = head
if nxt:
head = nxt
else:
break
return head
def merge_k_lists(lists: List[ListNode]) -> ListNode:
output = None
output_head = None
if len(lists) == 0:
return None
elif len(lists) == 1:
return lists[0]
heap = None
# Insert all ListNode values into our MinHeap
for node in lists:
while node:
v = node.val
if heap is None:
heap = MinHeap(v)
else:
heap.insert(v)
node = node.next
if heap is None:
return None
# Pop values off of the heap 1 by 1 to assemble merged list
popped = heap.pop()
while popped is not None:
if output is None:
output = ListNode(popped)
output_head = output
else:
output.next = ListNode(popped)
output = output.next
popped = heap.pop()
return output_head