【LeetCode】21. 合并两个有序链表

问题描述

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.

合并两个已排序的链表，并以新链表的形式返回。新列表应该通过将前两个列表的节点拼接在一起来创建。

输入: 1->2->4, 1->3->4
输出: 1->1->2->3->4->4

Python 实现

思路很简单，由于两个链表已经是有序的，因此只需要依次从两个链表取较小值的结点即可。

# Definition for singly-linked list.
# 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 == None:
            return l2
        if l2 == None:
            return l1
        
        head = ListNode(None)
        curNode = head
        p1 = l1
        p2 = l2
        
        # Merge from the second node.
        while p1 != None and p2 != None:
            if p1.val <= p2.val:
                curNode.next = p1
                p1 = p1.next
            else:
                curNode.next = p2
                p2 = p2.next
            curNode = curNode.next
        
        if p1 == None:
            curNode.next = p2
        else:
            curNode.next = p1
        
        # Skip the first empty node.
        return head.next
            

链接：https://leetcode.com/problems/merge-two-sorted-lists/

来源：CSDN

作者：Wyman蚊子

链接：https://blog.csdn.net/sinat_36645384/article/details/103473765