【LeetCode】Merge Two Sorted Lists

版权声明： https://blog.csdn.net/ysq96/article/details/89918244

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

题意：将两个有序的链表合并成为一个有序的链表

C++：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        ListNode* head=new ListNode(-1),*cur=head;
        while(l1&&l2){
            if(l1->val<l2->val){
                cur->next=l1;
                l1=l1->next;
            }else{
                cur->next=l2;
                l2=l2->next;
            }
            cur=cur->next;
        }
        cur->next=l1?l1:l2;
        return head->next;
    }
};

Python3：

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
        res=ListNode(None)
        node=res
        while l1 and l2:
            if l1.val<l2.val:
                node.next,l1=l1,l1.next
            else:
                node.next,l2=l2,l2.next
            node=node.next
        if l1:
            node.next=l1;
        else:
            node.next=l2;
        return res.next