# self.next = next
from ListNode import ListNode
class Solution:
def swapPairs(self, head: ListNode) -> ListNode:
pre = dummy = ListNode(-1, head)
while pre.next and pre.next.next:
# tmp = pre.next
# pre.next = pre.next.next
# tmp.next = pre.next.next
# pre.next.next = tmp
# pre = tmp
pre.next, pre.next.next, pre.next.next.next, pre =\
pre.next.next, pre.next, pre.next.next.next, pre.next
return dummy.next
def swapPairs2(self, head: ListNode) -> ListNode:
pre = dummy = ListNode(-1,head)
while (p1:=pre.next) and (p2:=pre.next.next):
pre.next, p2.next, p1.next, pre = p2, p1, p2.next, p1
return dummy.next
head = ListNode(1)
head.nextItm(2).nextItm(3).nextItm(4)
obj = Solution()
print(obj.swapPairs2(head))
return recur(head, None)
# put val into array
def sortedListToBST2(self, head: ListNode) -> TreeNode:
if not head:
return None
# put linked list into array
array = []
pos = head
while pos:
array.append(pos.val)
pos = pos.next
def transfer(beg: int, end: int) -> TreeNode:
if beg > end:
return None
mid = (beg + end) >> 1
root = TreeNode(array[mid])
root.left = transfer(beg, mid - 1)
root.right = transfer(mid + 1, end)
return root
return transfer(0, len(array) - 1)
head = ListNode(-10)
head.nextItm(-3).nextItm(0).nextItm(5).nextItm(9)
so = Solution()
so.sortedListToBST(head)
heap = [(head.val, idx, head) for idx, head in enumerate(lists)
if head]
heapq.heapify(heap)
while heap:
_, idx, node = heap[0]
cur.next = node
cur = cur.next
if node.next:
heapq.heapreplace(heap, (node.next.val, idx, node.next))
else:
heapq.heappop(heap)
cur.next = None
return dummy.next
lists = []
node1 = ListNode(1)
node1.nextItm(4).nextItm(5)
lists.append(node1)
node2 = ListNode(1)
node2.nextItm(3).nextItm(4)
lists.append(node2)
node3 = ListNode(2)
node3.nextItm(6)
lists.append(node3)
obj = Solution()
print(obj.mergeKLists(lists))
tail.next = next.next
pre.next = next
next.next = cur
return dummy.next
def insertionSortList2(self, head: ListNode) -> ListNode:
if not head:
return head
dummy = ListNode(-1)
dummy.next = head
tail = head
while tail.next:
# max
if tail.val < tail.next.val:
tail = tail.next
continue
cur = tail.next
tail.next = cur.next
p = dummy
while p.next.val < cur.val:
p = p.next
# insert
p.next, cur.next = cur, p.next
return dummy.next
head = ListNode(-1)
head.nextItm(5).nextItm(3).nextItm(4).nextItm(0)
so = Solution()
so.insertionSortList2(head)
