def test1(self):
for f in functions:
a = list_to_linkedlist([7, 2, 4, 3])
b = list_to_linkedlist([5, 6, 4])
node = f(a, b)
self.assertEqual(linkedlist_to_list(node), [7, 8, 0, 7],
f.__name__)
def test(self):
for f in functions:
l1 = list_to_linkedlist([2,3,5])
l2 = list_to_linkedlist([1,3,6])
merged = f([l1, l2])
self.assertEqual(linkedlist_to_list(merged), [1,2,3,3,5,6], f.__name__)
def test1(self):
for f in functions:
node1 = list_to_linkedlist([1, 2, 3, 4, 5])
node2 = list_to_linkedlist([1, 2, 3, 4, 5, 6])
node2.next.next.next = node1.next.next
self.assertEqual(f(node1, node2).val, 3, f.__name__)
def test1(self):
for f in functions:
node = list_to_linkedlist([1,2,2,1])
self.assertEqual(f(node), True, f.__name__)
self.assertEqual(linkedlist_to_list(node), [1,2,2,1], f.__name__)
def test1(self):
for f in functions:
a = list_to_linkedlist([2, 3, 5])
b = list_to_linkedlist([1, 4, 6])
self.assertEqual(linkedlist_to_list(f(a, b)), [1, 2, 3, 4, 5, 6],
f.__name__)
# k = s + m
# s = n*r - m
# s = (n-1)*r + (r-m)
# i.e. steps from start to cycle entry = steps from meet to cycle entry(r-m)
def detectCycle(self, head: Optional[ListNode]) -> Optional[ListNode]:
hasCycle = False
start = slow = fast = head
while fast and fast.next and fast.next:
fast = fast.next.next
slow = slow.next
if fast == slow:
hasCycle = True
break
if not hasCycle:
return None
while start != slow:
start = start.next
slow = slow.next
return start
# test
node = list_to_linkedlist([1, 2, 3, 4])
print(Solution().detectCycle(node))
# link node 4 to node 3
node.next.next.next.next = node.next.next
print(Solution().detectCycle(node).val)
# link node 1 to itself
node.next = node
print(Solution().detectCycle(node).val)
def test1(self):
for f in functions:
node = list_to_linkedlist([1, 2, 3, 3, 3, 4, 4, 5])
self.assertEqual(linkedlist_to_list(f(node)), [1, 2, 3, 4, 5],
f.__name__)
def test1(self):
for f in functions:
a = list_to_linkedlist([2, 4, 3])
b = list_to_linkedlist([5, 6, 4])
self.assertEqual(linkedlist_to_list(f(a, b)), [7, 0, 8],
f.__name__)
def test2(self):
for f in functions:
node = list_to_linkedlist([1, 2, 3, 4])
node.next.next.next.next = node.next.next
self.assertEqual(f(node), True, f.__name__)
def test1(self):
for f in functions:
node = list_to_linkedlist([1, 2, 3, 4])
self.assertEqual(f(node), False, f.__name__)
def test1(self):
for f in functions:
self.assertEqual(
linkedlist_to_list(f(list_to_linkedlist([1, 2, 3, 4, 5]))),
[5, 4, 3, 2, 1], f.__name__)