https://leetcode-cn.com/problems/add-two-numbers/
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最优解

  1. class Solution {
  2.     public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
  3.         int promo = 0;
  4.         ListNode newHead = new ListNode(0);
  5.         ListNode tmp = newHead;
  6.         ListNode tmp1 = l1, tmp2 = l2;
  7.         while (tmp1 != null || tmp2 != null || promo != 0) {
  8.             int val = promo;
  9.             if (tmp1 != null) {
  10.                 val += tmp1.val;
  11.                 tmp1 = tmp1.next;
  12.             }
  13.             if (tmp2 != null) {
  14.                 val += tmp2.val;
  15.                 tmp2 = tmp2.next;
  16.             }
  17.             tmp.next = new ListNode(val % 10);
  18.             promo = val / 10;
  19.             tmp = tmp.next;
  20.         }
  21.         return newHead.next;
  22.     }
  23. }

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