将两个有序链表合并为一个新的有序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
例如:
输入:1->2->4, 1->3->4
输出:1->1->2->3->4->4
class Solution:
def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
head = ListNode(None)
c=head
while l1 and l2:
if l1.val < l2.val:
c.next = l1
l1 = l1.next
else:
c.next = l2
l2 = l2.next
c = c.next
c.next = l1 if l1 else l2
return head.next
参考大神的解法:
class Solution:
def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
#参考官方题解,用递归,bulijie
if l1 is None:
return l2
elif l2 is None:
return l1
elif l1.val < l2.val:
l1.next = self.mergeTwoLists(l1.next , l2)
return l1
else:
l2.next = self.mergeTwoLists(l2.next , l1)
return l2
这个算法采用递归的思路,使代码简洁了很多。