题目描述
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
代码
思路:(!!链表的val和链表的next要区分开,分别赋值)就和归并排序差不多
# Definition for singly-linked list.
# class ListNode(object):
# def __init__(self, x):
# self.val = x
# self.next = None
def mergeTwoLists(l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
if l1 == None:
return l2
if l2 == None:
return l1
p = l1
q = l2
l3 = ListNode(None)
w = l3
while p != None or q != None:
if p == None:
w.val = q.val
w.next = q.next
break
elif q == None:
w.val = p.val
w.next = p.next
break
else:
if p.val <= q.val:
w.val = p.val
p = p.next
else:
w.val = q.val
q = q.next
tmp = ListNode(None)
w.next = tmp
w = tmp
return l3