Java 代码

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode merge(ListNode l1, ListNode l2) 
    {
        ListNode ln = new ListNode(-1);
        ListNode currNode = ln;

        while (l1 != null && l2 != null)
        {
            if (l1.val < l2.val)
            {
                currNode.next = l1;
                l1 = l1.next;
            }
            else
            {
                currNode.next = l2;
                l2 = l2.next;
            }
            currNode = currNode.next;
        }

        if (l1 != null)
        {
            currNode.next = l1;
        }
        if (l2 != null)
        {
            currNode.next = l2;
        }
        return ln.next;
    }
}