LeetCode - t2 - 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 addTwoNumbers(ListNode l1, ListNode l2) {
    
    
        ListNode l3=null,l3_1=null;
        ListNode begin=null;
        boolean flag=false;
        while(l1 != null || l2 != null || flag){
    
    
            l3=new ListNode(0);
            if(l3_1!=null){
    
    
                l3_1.next=l3;
            }
            if(begin==null){
    
    
                begin=l3;
            }
            if(l1!=null){
    
    
                l3.val+=l1.val;
                l1=l1.next;
            }
            if(l2!=null){
    
    
                l3.val+=l2.val;
                l2=l2.next;
            }
            if(flag==true){
    
    
                l3.val++;
                flag=false;
            }
            if(l3.val>=10){
    
    
                l3.val-=10;
                flag=true;
            }
            l3_1=l3;
        }
        return begin;
    }
}