def reorderList(self, head: ListNode) -> None:
"""
Do not return anything, modify head in-place instead.
"""
if not head:
return head
deque = []
pointer = head
while pointer:
deque.append(pointer)
pointer = pointer.next
p = deque.pop(0)
while deque:
p.next = deque.pop(-1)
p = p.next
if deque:
p.next = deque.pop(0)
p = p.next
p.next = None
prettyPrintLinkedList(head)
def isPalindrome(self, head: ListNode) -> bool:
if not head or head.next is None:
return True
p1 = p2 = head
while p2.next and p2.next.next:
p1 = p1.next
p2 = p2.next.next
h = p1.next
t = [p2, p2.next][p2.next is not None]
def reverse(subhead, tail):
if subhead == tail: # 相同则不需要翻转
return subhead, tail
current = subhead
nextnode = current.next
while nextnode.next: # 反指并移动指针
nextnxt = nextnode.next
nextnode.next = current
current = nextnode
nextnode = nextnxt
nextnode.next = current # 把最后一步指过来
return tail, subhead
h, t = reverse(h, t)
p1.next = h
t.next = None
p2 = head
prettyPrintLinkedList(head)
p1 = p1.next
while p1:
if p1.val != p2.val:
return False
p1 = p1.next
p2 = p2.next
return True
while nextnode.next: # 反指并移动指针
nextnxt = nextnode.next
nextnode.next = current
current = nextnode
nextnode = nextnxt
nextnode.next = current # 把最后一步指过来
return tail, subhead
h, t = reverse(h, t)
p1.next = h
t.next = None
p2 = head
prettyPrintLinkedList(head)
p1 = p1.next
while p1:
if p1.val != p2.val:
return False
p1 = p1.next
p2 = p2.next
return True
sol = Solution()
from L61_Rotate_List_linked_list_debug import stringToListNode, prettyPrintLinkedList
head = stringToListNode([1, 2, 3, 6, 2, 1])
head = stringToListNode([1])
prettyPrintLinkedList(head)
print(sol.isPalindrome(head))
"""
if not head:
return head
deque = []
pointer = head
while pointer:
deque.append(pointer)
pointer = pointer.next
p = deque.pop(0)
while deque:
p.next = deque.pop(-1)
p = p.next
if deque:
p.next = deque.pop(0)
p = p.next
p.next = None
prettyPrintLinkedList(head)
from L61_Rotate_List_linked_list_debug import stringToListNode, prettyPrintLinkedList
sol = Solution()
head = stringToListNode([0, 1, 2, 3, 4, 5, 6])
head = stringToListNode([])
prettyPrintLinkedList(head)
prettyPrintLinkedList(sol.reorderList(head))
if stack1 and stack2:
val1, val2 = stack1.pop(-1).val, stack2.pop(-1).val
elif stack1:
val1 = stack1.pop(-1).val
val2 = 0
else:
val1 = 0
val2 = stack2.pop(-1).val
val = (val1 + val2 + carry) % 10
carry = (val1 + val2 + carry) // 10
ret.append(ListNode(val))
if carry:
ret.append(ListNode(1))
ret.reverse()
for i, ele in enumerate(ret[:-1]):
ele.next = ret[i + 1]
return ret[0]
from L61_Rotate_List_linked_list_debug import stringToListNode, prettyPrintLinkedList
sol = Solution()
head1 = stringToListNode([])
prettyPrintLinkedList(head1)
head2 = stringToListNode([])
prettyPrintLinkedList(head2)
prettyPrintLinkedList(sol.addTwoNumbers(head1, head2))
if not head or not head.next:
return head # termination.
# cut the LinkedList at the mid index.
slow, fast = head, head.next
while fast and fast.next:
fast, slow = fast.next.next, slow.next
mid, slow.next = slow.next, None # save and cut.
# cut recursive.
left, right = self.sortList(head), self.sortList(mid)
# merge `left` and `right` linked list and return it.
h = res = ListNode(0)
while left and right:
if left.val < right.val:
h.next, left = left, left.next
else:
h.next, right = right, right.next
h = h.next
h.next = left if left else right
return res.next
from L61_Rotate_List_linked_list_debug import stringToListNode, prettyPrintLinkedList
head = stringToListNode([4, 5, 4, 3, 1, 0, 2])
head = stringToListNode([])
prettyPrintLinkedList(head)
sol = Solution()
prettyPrintLinkedList(sol.sortList(head))
while t and cnt < k:
t = t.next
cnt += 1
if t:
nxt = t.next
h, t = reverse(h, t)
# connect pre and nxt
pre.next = h
t.next = nxt
# prepare for next round
pre = t
h, t = nxt, nxt
return dummy.next
sol = Solution()
from L61_Rotate_List_linked_list_debug import stringToListNode, prettyPrintLinkedList
# head = stringToListNode([0, 1, 2, 4, 5, 6, 7, 8, 9, 10, 11])
# prettyPrintLinkedList(head)
# prettyPrintLinkedList(sol.reverseKGroup(head, 3))
head = stringToListNode([1, 2, 3, 4, 5])
prettyPrintLinkedList(head)
prettyPrintLinkedList(sol.reverseKGroup(head, -1))
# print(sol.reverseKGroup())