Leetcode 2 两数相加
题目地址:https://leetcode-cn.com/problems/add-two-numbers/
难度:简单
基本思路:
- 大于10要考虑进位,具体进几位用整除,当前结点大小用模除
- 要考虑两条链表不一样长度的情况,所以遍历的判断条件是有一个不为空则继续,二者皆空则停止
class Solution { // 与官方题解思路一致, 效率低是因为多创建了结点 public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode head = null, res = null; int carry = 0, val, l1Val, l2Val, sum; while(l1 != null || l2 != null){ l1Val = l1 == null ? 0 : l1.val; l2Val = l2 == null ? 0 : l2.val; sum = l1Val + l2Val + carry; val = sum % 10; carry = sum / 10; if(head == null){ res = head = new ListNode(val); }else{ res.next = new ListNode(val); res = res.next; } if(l1 != null){ l1 = l1.next; } if(l2 != null){ l2 = l2.next; } if(carry > 0){ res.next = new ListNode(carry); } } return head; } }
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