def reverse_k_group(head, k):
stack = deque()
fake_head = ListNode(None)
fake_head.next = head
group_head = fake_head
while True:
has_group = True
runner = group_head.next
for i in xrange(k):
if not runner:
has_group = False
break
stack.append(runner)
runner = runner.next
if not has_group:
return fake_head.next
group_tail = runner
next_head = group_head.next
while stack:
node = stack.pop()
group_head.next = node
group_head = group_head.next
group_head.next = group_tail
group_head = next_head
return fake_head.next
def _test(self, head, n, expected):
head = ListNode.from_array(head)
actual = Solution().removeNthFromEnd(head, n)
actual = ListNode.to_array(actual)
self.assertEqual(expected, actual)
def _test(self, root, k, expected):
root = ListNode.from_array(root)
actual = Solution().splitListToParts(root, k)
actual = [ListNode.to_array(node) for node in actual]
self.assertEqual(expected, actual)
def _test(self, head, k, expected):
head = ListNode.from_array(head)
actual = Solution().reverseKGroup(head, k)
actual = ListNode.to_array(actual)
self.assertEqual(expected, actual)
def partition(self, head: ListNode, x: int) -> ListNode:
if not head:
return head
pre = ListNode()
pre.next = head
cur = head
prefirst = pre
head = pre
firstGreater: ListNode = None
while cur:
if not firstGreater and cur.val >= x:
firstGreater = cur
if firstGreater and cur.val < x:
prefirst.next = cur
pre.next = cur.next
cur.next = firstGreater
prefirst = cur
cur = pre.next
continue
pre = pre.next
cur = cur.next
if not firstGreater:
prefirst = prefirst.next
return head.next
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
r = 0
prev = None
head = None
p, q = l1, l2
while (p is not None or q is not None):
i = p.val if p else 0
j = q.val if q else 0
x = i + j + r
r = x / 10
x = x % 10
n = ListNode(x)
prev = n
if p:
p = p.next
if q:
q = q.next
# Edge case, when 2 last number sum > 10
if r != 0:
n = ListNode(r)
if prev:
prev.next = n
return head
def _test(self, head, expected):
head = ListNode.from_array(head)
actual = Solution().sortList(head)
actual = ListNode.to_array(actual)
self.assertEqual(expected, actual)
def oddEvenList(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
odd_head = ListNode(0)
odd = odd_head
even_head = ListNode(0)
even = even_head
while True:
if not head:
break
odd.next = head
odd = head
head = head.next
if not head:
break
even.next = head
even = head
head = head.next
odd.next = even_head.next
even.next = None
return odd_head.next
def _test(self, head, x, expected):
head = ListNode.from_array(head)
actual = Solution().removeElements(head, x)
actual = ListNode.to_array(actual)
self.assertEqual(expected, actual)
def _test(self, l1, l2, expected):
l1 = ListNode.from_array(l1)
l2 = ListNode.from_array(l2)
actual = Solution().addTwoNumbers(l1, l2)
actual = ListNode.to_array(actual)
self.assertEqual(expected, actual)
def _test(self, node, expected):
node = ListNode.from_array(node)
Solution().deleteNode(node)
actual = ListNode.to_array(node)
self.assertEqual(expected, actual)
def removeElements2(self, head: ListNode, val: int) -> ListNode:
firstNode = ListNode(0)
firstNode.next = head
pre, cur = firstNode, head
while cur:
if cur.val == val:
pre.next = cur.next
else:
pre = cur
cur = cur.next
return firstNode.next
def swap_pairs(head):
fake_head = ListNode(None)
fake_head.next = head
prev = fake_head
while prev.next and prev.next.next:
r1 = prev.next
r2 = r1.next
r1.next = r2.next
prev.next = r2
r2.next = r1
prev = r
return fake_head.next
def _test(self, a, b_before_intersection, a_len_before_intersection):
a = ListNode.from_array(a)
b = ListNode.from_array(b_before_intersection)
intersection = a
for _ in range(a_len_before_intersection):
intersection = intersection.next
b_end = b
while b_end.next:
b_end = b_end.next
b_end.next = intersection
actual = Solution().getIntersectionNode(a, b)
self.assertEqual(intersection, actual)
def _sort(lo):
if not lo.next:
return lo
mid = lo
tail = lo
while tail and tail.next and tail.next.next:
mid = mid.next
tail = tail.next.next
hi = mid.next
mid.next = None
lo = _sort(lo)
hi = _sort(hi)
dummy = ListNode(0)
prev = dummy
while lo and hi:
if lo.val <= hi.val:
prev.next = lo
prev = lo
lo = lo.next
else:
prev.next = hi
prev = hi
hi = hi.next
if lo:
prev.next = lo
else:
prev.next = hi
return dummy.next
def mergeTwoLists(self, l1, l2): """ :type l1: ListNode :type l2: ListNode :rtype: ListNode """ if l1 is None: return l2 if l2 is None: return l1 # It's hard to merge l1 into l2 or l2 into l1 # The merging may be alternating # It's easier to form a new list dummyHead = ListNode(-1) runner = dummyHead while l1 and l2: if l1.val <= l2.val: runner.next = l1 l1 = l1.next runner = runner.next else: runner.next = l2 l2 = l2.next runner = runner.next if l1 is not None: runner.next = l1 if l2 is not None: runner.next = l2 return dummyHead.next
def partition(self, head: Optional[ListNode],
x: int) -> Optional[ListNode]:
dummy_lo = lo = ListNode(0)
dummy_hi = hi = ListNode(0)
while head:
if head.val < x:
lo.next = head
lo = head
else:
hi.next = head
hi = head
head = head.next
lo.next = dummy_hi.next
hi.next = None
return dummy_lo.next
def swapPairs(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
dummy = ListNode(0)
dummy.next = head
curr = dummy
while curr.next and curr.next.next:
a, b, c = curr.next, curr.next.next, curr.next.next.next
curr.next = b
b.next = a
a.next = c
curr = a
return dummy.next
def removeElements(self, head: ListNode, val: int) -> ListNode:
if not head:
return None
nxt = self.removeElements(head.next, val)
if head.val == val:
return nxt
head.next = nxt
return head
def test(self):
cases = utils.load_test_json(__file__).test_cases
for case in cases:
args = str(case.args)
head = ListNode.from_array(case.args.head)
actual = Solution().oddEvenList(head)
actual = ListNode.to_array(actual)
self.assertEqual(case.expected, actual, msg=args)
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
l1 = reverse_list(l1)
l2 = reverse_list(l2)
carry = 0
sum_root = ListNode(0)
sum_ = sum_root
while l1 and l2:
digit = l1.val + l2.val + carry
if digit >= 10:
digit -= 10
carry = 1
else:
carry = 0
node = ListNode(digit)
sum_.next = node
sum_ = node
l1 = l1.next
l2 = l2.next
if l2:
l1 = l2
while l1:
digit = l1.val + carry
if digit >= 10:
digit -= 10
carry = 1
else:
carry = 0
node = ListNode(digit)
sum_.next = node
sum_ = node
l1 = l1.next
if carry:
sum_.next = ListNode(carry)
return reverse_list(sum_root.next)
def sortList(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
n = count(head)
parent = ListNode(0)
parent.next = head
sublen = 1
while True:
new_sublen = sublen << 1
prev = parent
hi_node = prev.next
for lo in range(0, n, new_sublen):
lo_end = min(lo + sublen, n)
hi = lo_end
hi_end = min(hi + sublen, n)
lo_node = hi_node
for _ in range(hi - lo):
hi_node = hi_node.next
for _ in range(hi_end - lo):
if hi >= hi_end or lo < lo_end and lo_node.val <= hi_node.val:
prev.next = lo_node
prev = lo_node
lo_node = lo_node.next
lo += 1
else:
prev.next = hi_node
prev = hi_node
hi_node = hi_node.next
hi += 1
if new_sublen >= n:
break
sublen = new_sublen
prev.next = None
return parent.next
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
dummy = ListNode(0)
cur = dummy
carry = 0 # don't forget initialization
while l1 or l2 or carry:
if l1:
carry += l1.val
l1 = l1.next
if l2:
carry += l2.val
l2 = l2.next
cur.next = ListNode(carry % 10)
cur = cur.next
carry //= 10
return dummy.next
def mergeKLists(lists):
s = [x for x in lists if x is not None]
s = build_heap(s)
dummy = ListNode(None)
tmp = dummy
while len(s) > 0:
n = s[0]
if n is not None:
node = ListNode(n.val)
tmp.next = node
tmp = node
if n.next is None:
s = pop_heap(s)
else:
s[0] = n.next
heapify(s, 0)
head = dummy.next
return head
def removeNthFromEnd(self, head, n):
"""
:type head: ListNode
:type n: int
:rtype: ListNode
"""
dummy = ListNode(0)
dummy.next = head
lo = dummy
for _ in range(n):
head = head.next
while head:
head = head.next
lo = lo.next
lo.next = lo.next.next
return dummy.next
def _test(self, nums):
head = ListNode.from_array(nums)
solution = Solution(head)
iteration = 1000
hit = 0
for _ in range(iteration):
val = solution.getRandom()
if val == nums[0]:
hit += 1
self.assertAlmostEqual(1.0 / len(nums), float(hit) / iteration, places=1)
def process_args(args):
args.head = ListNode.from_array(args.head)
if args.pos >= 0:
cycle_start = args.head
for i in range(args.pos):
cycle_start = cycle_start.next
curr = cycle_start
while curr.next:
curr = curr.next
curr.next = cycle_start
del args.pos
def deleteDuplicates(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
if not head:
return None
parent = ListNode(head.val - 1)
parent.next = head
head = parent
while head.next and head.next.next:
val = head.next.val
if head.next.next.val == val:
next_ = head.next.next.next
while next_ and next_.val == val:
next_ = next_.next
head.next = next_
else:
head = head.next
return parent.next
def reverseKGroup(head, k):
"""
:type head: ListNode
:type k: int
:rtype: ListNode
"""
dummy = ListNode(0)
dummy.next = head
p = dummy
i = 1
node = head
while node:
next_node = node.next
print(i, node.data)
if i == k:
new_head, tail_node = reverse(head, k)
p.next = new_head
p = tail_node
tail_node.next = next_node
head = next_node
i = 0
node = next_node
i = i + 1
return dummy.next
def deleteDuplicates(self, head: ListNode) -> ListNode:
if not head or not head.next:
return head
node = ListNode(0)
node.next = head
pre, cur, nxt = node, head, head.next
while nxt:
rep = False
while nxt and cur.val == nxt.val:
rep = True
nxt = nxt.next
if rep:
pre.next = nxt
if not nxt:
break
else:
cur = nxt
nxt = nxt.next
else:
pre = pre.next
cur = cur.next
nxt = nxt.next
return node.next