【每日一题Day253】LC2两数相加 | 链表模拟

/**
 * 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 dummy = new ListNode(-1);
        ListNode cur = dummy;
        int cnt = 0;
        while (l1 != null || l2 != null || cnt != 0){
            int a = 0, b = 0;
            if (l1 != null){
                a = l1.val;
                l1 = l1.next;
            }
            if (l2 != null){
                b = l2.val;
                l2 = l2.next;
            }
            int c = (a + b + cnt) % 10;
            cnt = (a + b + cnt) / 10;
            cur.next = new ListNode(c);
            cur = cur.next;
        }
        return dummy.next;
    }
}