LeetCode | 21. Merge Two Sorted Lists

题目描述

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.

Example:

Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4

思路

新建一个0节点用于存储结果

如果l1.val>l2.val，l1节点向后移一位
否则，l2节点向后移一位

代码

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode ans = new ListNode(0);
        ListNode cur = ans;
        while(l1!=null && l2!=null) {
            if(l1.val<l2.val) {
                cur.next = l1;
                l1 = l1.next;
            }
            else {
                cur.next = l2;
                l2 = l2.next;
            }
            cur = cur.next;
        }
        if(l1!=null) {
            cur.next = l1;
        }
        if(l2!=null) {
            cur.next = l2;
        }
        return ans.next;
    }
}

Beats 100%