2.add-two-numbers.go

/*
 * @lc app=leetcode id=2 lang=golang
 *
 * [2] Add Two Numbers
 *
 * https://leetcode.com/problems/add-two-numbers/description/
 *
 * algorithms
 * Medium (33.51%)
 * Likes:    8176
 * Dislikes: 2084
 * Total Accepted:    1.4M
 * Total Submissions: 4.2M
 * Testcase Example:  '[2,4,3]\n[5,6,4]'
 *
 * 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.
 *
 *
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
	carry, dummy := 0, &ListNode{}
	for node := dummy; l1 != nil || l2 != nil || carry > 0; node = node.Next {
		if l1 != nil {
			carry += l1.Val
			l1 = l1.Next
		}
		if l2 != nil {
			carry += l2.Val
			l2 = l2.Next
		}
		node.Next = &ListNode{carry % 10, nil}
		carry = carry / 10
	}
	return dummy.Next
}

// @lc code=end