Leetcode t21 - java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    
    
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
    
    
        ListNode l3=null,begin=null;
        while(l1!=null || l2!=null)
        {
    
    
            int now;
            if(l1!=null && l2!=null)
            {
    
    
                if(l1.val<=l2.val){
    
    
                    now=l1.val;
                    l1=l1.next;
                }
                else{
    
    
                    now=l2.val;
                    l2=l2.next;
                }
            }
            else if(l1!=null)
            {
    
    
                now=l1.val;
                l1=l1.next;
            }
            else
            {
    
    
                now=l2.val;
                l2=l2.next;
            }
            if(l3==null)
            {
    
    
                l3=new ListNode(now);
                begin=l3;
            }
            else
            {
    
    
                l3.next=new ListNode(now);
                l3=l3.next;
            }
        }
        return begin;
    }
}