LeetCode-002两数相加(Add Two Numbers)

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博客围绕LeetCode-002题目展开，该题要求将两个逆序存储数字的非空链表相加，返回表示和的新链表。给出示例及解题思路，还提及Java实现的执行用时和内存消耗情况，作者刚开始刷LeetCode，后续会改进效率并记录。

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LeetCode-002

You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

Solution

class Solution {
	Integer carry=0;
	public ListNode addTwoNumbers(ListNode l1,ListNode l2) {
		ListNode sol=new ListNode(-1);
		ListNode solution=sol;
		if (l1==null||l2==null)
			return l1!=null?l1:l2;
		while (l1!=null) {
			if (l2!=null) {
				sol.next=new ListNode(l1.val+l2.val+carry);
				sol.next.val=plusCarry(sol.next.val);
				l1=l1.next;
				l2=l2.next;
			}
			else {
				sol.next=new ListNode(l1.val+carry);
				sol.next.val=plusCarry(sol.next.val);
				l1=l1.next;
			}
			sol=sol.next;
		}
		while (l2!=null||carry!=0) {
			sol.next=new ListNode((l2==null?0:l2.val)+carry);
			sol.next.val=plusCarry(sol.next.val);
			l2=l2==null?null:l2.next;
			sol=sol.next;
		}
		return solution.next;
	}
	public int plusCarry(int val) {
		if (val>=10) {
			val-=10;
			carry=1;
		}
		else 
			carry=0;
		return val;
	}
}