版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/aBIT_Tu/article/details/83615261
参考了这个博主的答案(https://blog.csdn.net/gleam_/article/details/80149010),之前递归一直学的不是太好,但真的想通了以后写起来很神清气爽。
1. 递归的思路
# 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
"""
if l1==None and l2==None:
return None
if l1==None:
return l2
if l2==None:
return l1
if l1.val<=l2.val:
l1.next=self.mergeTwoLists(l1.next,l2)
return l1
else:
l2.next=self.mergeTwoLists(l1,l2.next)
return l2
2. 非递归(这个是参看这个博主小哥的,https://blog.csdn.net/honeyaya/article/details/52915759)
# -*- coding:utf-8 -*-
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
# 返回合并后列表
def Merge(self, pHead1, pHead2):
# write code here
if pHead1==None and pHead2==None:
return None
elif pHead1!=None and pHead2==None:
return pHead1
elif pHead1==None and pHead2!=None:
return pHead2
else:
p1=pHead1
p2=pHead2
if p1.val<p2.val:
newHead=p1
p1=p1.next
else:
newHead=p2
p2=p2.next
p=newHead
while p1!=None and p2!=None:
if p1.val<p2.val:
p.next=p1
p=p.next
p1=p1.next
else:
p.next=p2
p=p.next
p2=p2.next
if p1!=None:
while p1!=None:
p.next=p1
p1=p1.next
p=p.next
if p2!=None:
while p2!=None:
p.next=p2
p2=p2.next
p=p.next
return newHead
!