就像一个贪吃蛇将两个链表一一的吃进来

class Solution(object):def mergeTwoLists(self, list1, list2):""":type list1: Optional[ListNode]:type list2: Optional[ListNode]:rtype: Optional[ListNode]"""p = ListNode(0)cur = pwhile list1 and list2:if list1.val >= list2.val:cur.next = list2list2 = list2.nextcur = cur.nextelse:cur.next = list1list1 = list1.nextcur = cur.nextif list1 is None:cur.next = list2else:cur.next = list1# while list1:#     cur.next = list1#     list1 = list1.next#     cur = cur.next# while list2:#     cur.next = list2#     list2 = list2.next#     cur = cur.nextreturn p.next