标签：
[Problem]
You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
[Analysis]
这题的思路比较简单，只需要把两个ListNode相加可能出现的四种情况列清楚：
1. L1 != null && L2 != null
2. L1 != null && L2 == null
3. L1 ==? null && L2 != null
4. ?L1 == L2 == null && carry == 1
[Solution]
public class Solution { public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode currentNode = new ListNode(0); return addTwoNumbers(l1, l2, currentNode, 0).next; } public ListNode addTwoNumbers(ListNode l1, ListNode l2, ListNode currentNode, int carry) { int val1 = 0; int val2 = 0; if (l1 != null) { val1 = l1.val; l1 = l1.next; if (l2 != null) { val2 = l2.val; l2 = l2.next; } } else { if (l2 != null) { val2 = l2.val; l2 = l2.next; } else { if (carry != 0) { currentNode.next = new ListNode(carry); } return currentNode; } } int val = val1 + val2 + carry; ListNode newNode = new ListNode(val % 10); currentNode.next = addTwoNumbers(l1, l2, newNode, val/10); return currentNode; } }
LeetCode #2 Add Two Numbers (M)
标签：
原文地址：http://www.cnblogs.com/zhangqieyi/p/4850495.html
