Merge Sorted Lists

Merge sorted linked lists and return it as a new list. The new list should is made by splicing together the nodes of the first of the lists.

This problem is similar to the add two numbers, noting that there are unequal lengths, and considering the use of dummy node as the result of the head element, the time complexity O (n+m), n is the length of the two linked list respectively. Space complexity O (1). The code is as follows:

classsolution (object):defmergetwolists (self, L1, L2):""": Type L1:ListNode:type l2:ListNode:rtype:ListNode"""        if  notL1 and  notL2:returnNone Dummy= ListNode (-1) cur=Dummy whileL1 andL2:ifL1.val <L2.val:cur.next=ListNode (l1.val) L1=L1.nextElse: Cur.next=ListNode (l2.val) L2=L2.next cur=Cur.next Cur.next= L1ifL1ElseL2returnDummy.next

Merge Sorted Lists