def detectCycle2(self, head):
"""
检测链表是否有环，O(1)空间复杂度
:type head: ListNode
:rtype: bool
"""
if not head:
return None
fast = head
slow = head
while fast and fast.next and slow:
fast = fast.next.next
slow = slow.next
if fast == slow:
break
if not fast or not fast.next:
return None
fast = head
while fast != slow:
fast = fast.next
slow = slow.next
return fast
if __name__ == '__main__':
head = ListNode.create_linked_list([1, 2, 3])
# head.next.next.next = head
res = Solution().detectCycle2(head)
print(res is not None)
class Solution(object):
def deleteDuplicates(self, head):
"""
删除重复的节点
:type head: ListNode
:rtype: ListNode
"""
temp = head
pre = None
while temp:
if temp.next and temp.val == temp.next.val:
t = temp.next
while t and temp.val == t.val:
t = t.next
temp = t
if not pre:
head = temp
else:
pre.next = temp
else:
pre = temp
temp = temp.next
return head
if __name__ == '__main__':
list = ListNode.create_linked_list([1, 2, 3, 3, 4, 4, 5])
result = Solution().deleteDuplicates(list)
print(result)
return head.next
def mergeKLists3(self, lists):
"""
合并多个排序好的列表
:type lists: List[ListNode]
:rtype: ListNode
"""
node_list = []
for node in lists:
while node:
node_list.append(node)
node = node.next
if not node_list:
return []
node_list = sorted(node_list, key=lambda x: x.val)
head = cur = ListNode(0)
for node in node_list:
cur.next = node
cur = node
return head.next
if __name__ == '__main__':
input = [
ListNode.create_linked_list([0]),
ListNode.create_linked_list([1]),
]
result = Solution().mergeKLists3(input)
print(result)
合并两个有序链表
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
t1 = l1
t2 = l2
cur = head = ListNode(0)
while t1 or t2:
if not t1:
cur.next = ListNode(t2.val)
t2 = t2.next
elif not t2:
cur.next = ListNode(t1.val)
t1 = t1.next
elif t1.val < t2.val:
cur.next = ListNode(t1.val)
t1 = t1.next
else:
cur.next = ListNode(t2.val)
t2 = t2.next
cur = cur.next
return head.next
if __name__ == '__main__':
list1 = ListNode.create_linked_list([2, 3])
list2 = ListNode.create_linked_list([1, 2])
result = Solution().mergeTwoLists(list1, list2)
print(result)
"""
将两个链表形式的数字相加
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
t1 = l1
t2 = l2
cur = head = ListNode(0)
d = 0
while t1 or t2:
cur.next = ListNode(0)
cur = cur.next
val1 = t1.val if t1 else 0
val2 = t2.val if t2 else 0
d, cur.val = divmod(val1 + val2 + d, 10)
if t1:
t1 = t1.next
if t2:
t2 = t2.next
if d:
cur.next = ListNode(d)
return head.next
if __name__ == '__main__':
l1 = ListNode.create_linked_list([1, 1])
l2 = ListNode.create_linked_list([9, 9])
result = Solution().addTwoNumbers(l1, l2)
print(result)
