Someone

n = degree
c = coefficient
prev = root
node = root

while node:
	if node->degree == n:
		if c == 0:
			prev->next = node.next
			delete (node)
		else:
			node.coefficient = c
	elif n > node->degree: # since we traverse the list in ascending order
		if c != 0:
			temp = Node(n, c)
			temp->next = node->next
			node->next = temp
		break

	prev = node
	node = node->next