题解 | #链表相加(二)#

package main

import . "nc_tools"

/*
 * type ListNode struct{
 *   Val int
 *   Next *ListNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param head1 ListNode类
 * @param head2 ListNode类
 * @return ListNode类
 */
func addInList(head1 *ListNode, head2 *ListNode) *ListNode {
	// write code here
	if head1 == nil {
		return head2
	}
	if head2 == nil {
		return head1
	}
	virtualHead := &ListNode{}
	cur := virtualHead

	reverse1 := ReverseLink(head1)
	reverse2 := ReverseLink(head2)
	canary := 0

	for i := 0; ; i++ {
		if reverse1 != nil || reverse2 != nil || canary != 0 {
			node := &ListNode{}
			var v1 int
			var v2 int
			if reverse1 != nil {
				v1 = reverse1.Val
			} else {
				v1 = 0
			}

			if reverse2 != nil {
				v2 = reverse2.Val
			} else {
				v2 = 0
			}
			node.Val = (v1 + v2 + canary) % 10
			canary = (v1 +v2 + canary) / 10
			cur.Next = node
			cur = cur.Next
			if reverse1 != nil {
				reverse1 = reverse1.Next
			}
			if reverse2 != nil {
				reverse2 = reverse2.Next
			}
		} else {
			break
		}
	}
	return ReverseLink(virtualHead.Next)
}

func ReverseLink(head *ListNode) *ListNode {
	virtural := &ListNode{}
	virtural.Next = head
	for i := 0; ; i++ {
		if head == nil || head.Next == nil {
			break
		}
		next := head.Next
		head.Next = next.Next
		next.Next = virtural.Next
		virtural.Next = next
	}
	return virtural.Next
}