剑指offer-25-合并两个排序链表-golang

题目：输入两个递增排序的链表，合并这两个链表并使新链表中的节点仍然是递增排序的。

type Node struct {
	val  int
	next *Node
}

func union(head1 *Node, head2 *Node) *Node {
	if head1 == nil {
		return head2
	}
	if head2 == nil {
		return head1
	}
	head := &Node{}
	h := head
	p, q := head1, head2
	for p != nil && q != nil {
		if p.val < q.val {
			h.next = p
			h = p
			p = p.next
		} else {
			h.next = q
			h = q
			q = q.next
		}
	}
	if q == nil {
		h.next = p
	}
	if p == nil {
		h.next = q
	}
	return head.next
}