[LeetCode By Python] 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.
Example:

Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4

代码＋测试代码：

class ListNode(object):
def __init__(self, x):
self.val = x
self.next = None

class Solution(object):
def mergeTwoLists(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
if l1==l2==None:
return None
if l1 == None:
return l2
if l2 == None:
return l1

results = ListNode(0)
resultsf = results
while l1 and l2:
if l1.val <=l2.val:
resultsf.next = l1
l1 = l1.next
else:
resultsf.next = l2
l2 = l2.next
resultsf = resultsf.next
resultsf.next = l1 or l2
return results.next

if __name__ == '__main__':
l1_1 = ListNode(1)
l1_2 = ListNode(2)
l1_3 = ListNode(4)
l1_1.next = l1_2
l1_2.next = l1_3

l2_1 = ListNode(1)
l2_2 = ListNode(3)
l2_3 = ListNode(4)
l2_1.next = l2_2
l2_2.next = l2_3

l3 = Solution().mergeTwoLists(None,None)
while l3 !=None:
print l3.val
l3 = l3.next