def test_add(self):
linked = LinkedList()
linked.add(5)
self.assertIsNotNone(linked.head)
self.assertIsNotNone(linked.tail)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, 5)
def test_remove__from_tail(self):
linked = LinkedList()
linked.add(5)
linked.add(0)
linked.add(-1)
linked.remove(2)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, 0)
def test_remove__many_elements_list(self):
linked = LinkedList()
linked.add(5)
linked.add(0)
linked.add(-1)
linked.remove(1)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, -1)
linked.remove(1)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, 5)
def sort_k_linked_lists(*linked_lists):
min_heap = heap.Heap(comp=lambda x, y: x.value < y.value)
for lst in linked_lists:
min_heap.insert(lst.head)
result = LinkedList()
while len(min_heap.items) > 0:
item = min_heap.extract_min()
if item.next:
min_heap.insert(item.next)
result.add(item.value)
return result
def merge(list1, list2):
"""
This solution creates a new linked list and adds new node values while iterating on the two
linked lists. When we find that an element of the first list is less than the one of the
second, then we add a new node with the same value as the first and progress the pointer.
Otherwise, we do the same for the other list. When one of the two pointers comes to tail,
we copy the remaining items from the other list.
Complexity in time is O(n + m) where n and m are the lengths of the 2 lists. Complexity in
space is O(n + m) as well.
"""
c1 = list1.head
c2 = list2.head
merged = LinkedList()
while c1 and c2:
if c1.value < c2.value:
merged.add(c1.value)
c1 = c1.next
else:
merged.add(c2.value)
c2 = c2.next
while c1:
merged.add(c1.value)
c1 = c1.next
while c2:
merged.add(c2.value)
c2 = c2.next
return merged
def test_add__consecutive(self):
linked = LinkedList()
linked.add(5)
self.assertIsNotNone(linked.head)
self.assertIsNotNone(linked.tail)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, 5)
linked.add(0)
self.assertIsNotNone(linked.head)
self.assertIsNotNone(linked.tail)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, 0)
linked.add(-1)
self.assertIsNotNone(linked.head)
self.assertIsNotNone(linked.tail)
self.assertEqual(linked.head.value, 5)
self.assertEqual(linked.tail.value, -1)
def test_remove__single_element_list(self):
linked = LinkedList()
linked.add(5)
linked.remove(0)
self.assertIsNone(linked.head)
self.assertIsNone(linked.tail)
if fast.next is None or fast.next.next is None:
return
fast = fast.next.next
if slow == fast:
break
if slow.next is None:
return
slow = lst.head
while slow != fast:
slow = slow.next
fast = fast.next
return slow
if __name__ == '__main__':
lst = LinkedList()
lst.add('1')
print get_start_of_loop(lst)
lst = LinkedList()
lst.add('a').add('b').add('c').add('d').add('e').add('f')
lst.tail.next = lst.head.next.next
print get_start_of_loop(lst)
lst = LinkedList()
lst.add('0').add('a').add('b').add('c').add('d').add('e').add('f').add('g').add('h')
lst.tail.next = lst.head.next.next
print get_start_of_loop(lst)
