题解 | #合并k个已排序的链表#

class Solution:
    def mergeKLists(self , lists: List[ListNode]) -> ListNode:
        # write code here
        n=lists.__len__()
        if n==0:
            return None
        
        elif n==1:
            return lists[0]
        
        elif n==2:
            pHead1=lists[0]
            pHead2=lists[1]
            if pHead1==None:
                return pHead2
            elif pHead2==None:
                return pHead1
            if pHead1.val<=pHead2.val:
                p1=pHead1
                p2=pHead2
                p3=p1
            else:
                p1=pHead2
                p2=pHead1
                p3=p1

            while p2!=None and p1.next!=None:
                if p2.val<p1.next.val:
                    p2.next,p1.next,p2=p1.next,p2,p2.next
                p1=p1.next

            if p1.next==None:
                p1.next=p2
            return p3 
        
        else:
            lists2=[self.mergeKLists(lists[0:(n//2)]),self.mergeKLists(lists[(n//2):n])]
            return self.mergeKLists(lists2)