原题地址：https://oj.leetcode.com/problems/merge-two-sorted-lists/
题意：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.
解题思路：合并两个已经排好序的链表。
代码：
# Definition for singly-linked list. # class ListNode: # def __init__(self, x): # self.val = x # self.next = None class Solution: # @param two ListNodes # @return a ListNode def mergeTwoLists(self, l1, l2): if l1 == None: return l2 if l2 == None: return l1 dummy = ListNode(0) tmp = dummy while l1 and l2: if l1.val <= l2.val: tmp.next = l1 l1 = l1.next tmp = tmp.next else: tmp.next = l2 l2 = l2.next tmp = tmp.next if l2 == None: tmp.next = l1 else: tmp.next = l2 return dummy.next