// POST api/employees
public void Post(Employee employee)
{
int maxId = list.Max(e => e.Id);
employee.Id = maxId + 1;
list.Add(employee);
}
// PUT api/employees/12345
public void Put(int id, Employee employee)
{
int index = list.ToList().FindIndex(e => e.Id == id);
list[index] = employee;
}