链表求和

你有两个用链表代表的整数，其中每个节点包含一个数字。数字存储按照在原来整数中相反的顺序，使得第一个数字位于链表的开头。写出一个函数将两个整数相加，用链表形式返回和。

您在真实的面试中是否遇到过这个题？ 

Yes

样例

给出两个链表 3->1->5->null 和 5->9->2->null，返回 8->0->8->null

 

题目地址

/**
 * 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
        ListNode node = new ListNode(0);
        ListNode result = node;
        int text = 0;
        while(l1!=null && l2!=null){
            int sum = l1.val + l2.val + text;
            text = sum/10;
            sum = sum%10;
            node.next = new ListNode(sum);
            node = node.next;
            l1 = l1.next;
            l2 = l2.next;
        }
        while(l2 !=null){
            int sum = l2.val +text;
            text = sum/10;
            sum = sum%10;
            node.next = new ListNode(sum);
            node = node.next;
            l2 = l2.next;
        }
        while(l1 !=null){
            int sum = l1.val + text;
            text = sum/10;
            sum = sum%10;
            node.next = new ListNode(sum);
            node = node.next;
            l1 = l1.next;
        }
        if(text == 1){
            node.next = new ListNode(1);
            node = node.next;
        }
        return result.next;
    }
}