Implementation of leetcode two number addition go

The goal is ： Addition of two numbers

Here are two for you Non empty The linked list of , Represents two nonnegative integers . Each of them is based on The reverse Stored in , And each node can only store a Numbers .

Please add up the two numbers , And returns a linked list representing sum in the same form .

You can assume that in addition to the numbers 0 outside , Neither of these numbers 0 start .

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Result output ：

Here we mainly study the linked list operation and the carry of the last bit, which need to be considered carefully .

func addTwoNumbers(l1, l2 *ListNode) (head *ListNode) {
    
	var tail *ListNode
	carry := 0
	for l1 != nil || l2 != nil {
    
		n1, n2 := 0, 0
		if l1 != nil {
    
			n1 = l1.Val
			l1 = l1.Next
		}
		if l2 != nil {
    
			n2 = l2.Val
			l2 = l2.Next
		}
		sum := n1 + n2 + carry
		sum, carry = sum%10, sum/10
		if head == nil {
    
			// Create a node head
			head = &ListNode{
    Val: sum}
			// The position where the head node is equal to the tail node 
			tail = head
		} else {
    
			// The tail pointer points to the position of the new node 
			tail.Next = &ListNode{
    Val: sum}
			// Tail node pointed to by tail pointer 
			tail = tail.Next
		}
	}
	if carry > 0 {
    
		tail.Next = &ListNode{
    Val: carry}
	}
	return
}