LC2 - 两数相加

package LinkedList

func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
    virtualHead := new(ListNode)
    tail := virtualHead
    carry := 0
    for l1 != nil || l2 != nil {
        if l1 == nil {
            l1 = new(ListNode)
        }
        if l2 == nil {
            l2 = new(ListNode)
        }
        sum := (l1.Val + l2.Val + carry) % 10
        tail.Next = new(ListNode)
        tail = tail.Next
        tail.Val = sum
        carry = (l1.Val + l2.Val + carry) / 10
        l1 = l1.Next
        l2 = l2.Next
    }
    if carry == 1 {
        tail.Next = new(ListNode)
        tail = tail.Next
        tail.Val = 1
    }
    return virtualHead.Next
}

通过创建虚拟节点，模拟位数不足时的高位补零。