21. Merge Two Sorted Lists

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

Java

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { *         val = x; *         next = null; *     } * } */public class Solution {    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        ListNode head = new ListNode(0);        ListNode p=head, p1=l1, p2=l2;        while(p1!=null&&p2!=null){            if(p1.val<p2.val){p.next=p1; p1=p1.next;}            else{p.next=p2; p2=p2.next;}            p=p.next;        }        if(p1!=null) p.next = p1;        else if(p2!=null) p.next=p2;        return head.next;    }}

python

# Definition for singly-linked list.# class ListNode(object):#     def __init__(self, x):#         self.val = x#         self.next = Noneclass Solution(object):    def mergeTwoLists(self, l1, l2):        """        :type l1: ListNode        :type l2: ListNode        :rtype: ListNode        """        head=ListNode(0); dup=head;        while l1!=None and l2!=None :            if l1.val < l2.val :                dup.next=l1                l1 = l1.next                dup = dup.next            else:                dup.next=l2                l2 = l2.next                dup = dup.next                if l2==None and l1!=None:            dup.next=l1        elif l1==None and l2!=None:            dup.next=l2        return head.next