LeetCode Golang 单向链表相加 反向实现

LeetCode 两数之和, 反向实现

     1 -> 2 -> 3 -> 4

+                  3 -> 4

----------------------------

     1 -> 2 -> 6 -> 8

func addTwoNumbersReverse(l1 *ListNode, l2 *ListNode) *ListNode {
	if l1 == nil || l2 == nil {
		return nil
	}

	l := new(ListNode)
	l.Val = 0
	tmp := l
	flag := 0
	l1Arr := []int{}
	l2Arr := []int{}
	lRst := []int{}

	for l1 != nil {

		l1Arr = append(l1Arr, l1.Val)
		l1 = l1.Next
	}

	for l2 != nil {

		l2Arr = append(l2Arr, l2.Val)
		l2 = l2.Next
	}


	i := 0
	for {
		if i > len(l1Arr)-1 || i > len(l2Arr)-1 {

			break
		}
		num := l1Arr[i]+l2Arr[i]+flag
		flag = 0
		if num >= 10 {
			flag = 1
			num = num % 10
		}
		lRst = append(lRst,num)
		i++
	}

	if i < len(l1Arr) {
		for ;i<len(l1Arr);i++{
			if flag == 1 {
				lRst = append(lRst,l1Arr[i]+1)
				flag = 0
			} else {
				lRst = append(lRst,l1Arr[i])
			}
		}
	}

	if i < len(l2Arr) {
		for ;i<len(l2Arr);i++{
			if flag == 1 {
				lRst = append(lRst,l2Arr[i]+1)
				flag = 0
			} else {
				lRst = append(lRst,l2Arr[i])
			}
		}
	}

	for i := len(lRst)-1; i >=0; i-- {
		tmp.Val = lRst[i]
		if i == 0 {
			break
		}
		tmp.Next = new(ListNode)
		tmp = tmp.Next
	}
	return l
}

　　思路: 为了简化运算把所有链表中的值取出来到切片里进行相加, 然后再从切片写入到新的链表里

       另一个思路: 借助昨天的代码, 再运算前对链表进行反转