LintCode167:链表求和

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;      
 *     }
 * }
 */


public class Solution {
    /*
     * @param l1: the first list
     * @param l2: the second list
     * @return: the sum list of l1 and l2 
     */
    public ListNode addLists(ListNode l1, ListNode l2) {
        // write your code here
        if(l1==null&&l2==null){
            return null;
        }
        if(l1==null&&l2!=null){
            return l2;
        }
        if(l1!=null&&l2==null){
            return l1;
        }
        int count = 0;
         ListNode head = null;
        if(l1.val+l2.val+count>=10){
         head = new ListNode(l1.val+l2.val-10);
        count = 1;
        }else{
         head = new ListNode(l1.val+l2.val+count);
        }
        ListNode temp = head;
       
        while(l1.next!=null&&l2.next!=null){
            if(l1.next.val+l2.next.val+count>=10){
            temp.next = new ListNode(l1.next.val+l2.next.val+count-10);
            count=1;
            }else{
              temp.next = new ListNode(l1.next.val+l2.next.val+count);
              count=0;
            }
            temp = temp.next;
            l1 = l1.next;
            l2 = l2.next;
        }
       //加入还没循环结束的链表元素 
        while(l1.next!=null){
            if(l1.next.val+count>=10){
            temp.next = new ListNode(l1.next.val+count-10);
            count =1;
            }else{
           temp.next = new ListNode(l1.next.val+count);     
            count = 0;
            }
            temp = temp.next;
            l1 = l1.next;
        }
        while(l2.next!=null){
            if(l2.next.val+count>=10){
            temp.next = new ListNode(l2.next.val+count-10);
            count = 1;
             }else{
                temp.next = new ListNode(l2.next.val+count); 
                count = 0;   
             }
            temp = temp.next;
            l2 = l2.next;
        }
        if(count!=0){
            temp.next = new ListNode(1);
        }
        return head;
    }
}