关于环形复杂度的问题

[elegant_xiao]

    public void Method(DayOfWeek day)
    {

        switch (day)
        {
            case DayOfWeek.Monday:
                Console.WriteLine("Today is Monday!");
                break;
            case DayOfWeek.Tuesday:
                Console.WriteLine("Today is Tuesday!");
                break;
            case DayOfWeek.Wednesday:
                Console.WriteLine("Today is Wednesday!");
                break;
            case DayOfWeek.Thursday:
                Console.WriteLine("Today is Thursday!");
                break;
            case DayOfWeek.Friday:
                Console.WriteLine("Today is Friday!");
                break;
            case DayOfWeek.Saturday:
                Console.WriteLine("Today is Saturday!");
                break;
            case DayOfWeek.Sunday:
                Console.WriteLine("Today is Sunday!");
                break;
        }
    }

}

请问以上程序的环形复杂度为多少？MSDN上给出的是4，但不知如何得来.

[mygodsos]

路过帮顶
=============
11月6日，论坛升级公告，积分已经做了调整！
http://topic.csdn.net/u/20081107/11/b27dc75f-14b1-4594-9de3-5b18d9e36a11.html
此次调整增加了两个新的可用分获取渠道：
1：帖子被推荐（加精）后，帖主可以获得88分的可用分奖励；
2：帖子结帖后会返还帖主50%的悬赏分，无满意结帖不返还分数；
3：接下来会不断增加新的可用分获取途径，比如参与活动赠送等，请大家多关注；