LeetCode--Merge Two Sorted Lists

題目：

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.

解決方案：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode lr=new ListNode(0);
        ListNode temp=lr;
        if(l1==null){
            return l2;
        }
        if(l2==null){
            return l1;
        }
            while(l1!=null||l2!=null){
                boolean isl1=true;
                if(l1!=null&&l2!=null){
                    if(l1.val>=l2.val){
                        isl1=false;
                    }
                }else if(l1==null){
                    isl1=false;
                }
              if(isl1){
                  temp.next=l1;
                  l1=l1.next;
              }else{
                  temp.next=l2;
                  l2=l2.next;
              }
              temp=temp.next;
            }
       return  lr.next;
    }
}