【LeetCode】合并两个有序链表

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。 

示例：

输入：1->2->4, 1->3->4
输出：1->1->2->3->4->4

# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution:
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        rnode = ListNode(0)
        cur = rnode
        while l1 != None:
            if l2==None:
                cur.next = l1
                return rnode.next
            if l1.val >= l2.val:
                cur.next = l2
                cur = cur.next
                l2 = l2.next
            else:
                cur.next = l1
                cur = cur.next
                l1 = l1.next
        if l2:
            cur.next = l2
        
        return rnode.next