所有Leetcode题目不定期汇总在 Github, 欢迎大家批评指正，讨论交流。
'''
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
'''
# 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
"""
# Approach one 递归的方法
# if l1 == None:
# return l2
# elif l2 == None:
# return l1
# if l2.val >= l1.val:
# l1.next = self.mergeTwoLists(l1.next, l2)
# return l1
# else:
# l2.next = self.mergeTwoLists(l1, l2.next)
# return l2
# Approach two # 循环的解法需要两个新头结点，并注意拼接尾链
head = curr = ListNode(0)
while l1 and l2:
if l1.val >= l2.val:
curr.next = l2
l2 = l2.next
else:
curr.next = l1
l1 = l1.next
curr = curr.next
curr.next = l1 if l1 else l2
return head.next
进阶版题目 合并K个有序链表
所有Leetcode题目不定期汇总在 Github, 欢迎大家批评指正，讨论交流。
