protected internal void T()
{
    Dictionary<int, int> p2 = new Dictionary<int, int>();
    Add(p2, 1);
    Add(p2, 1);
    Add(p2, 2);
    Add(p2, 3);
    Add(p2, 4);
    Add(p2, 5);
    Add(p2, 6);
    Add(p2, 13);
    Add(p2, 12);
    Add(p2, 11);
    Add(p2, 12);
    Add(p2, 11);
    Add(p2, 12);
    Interaction.MsgBox("1出现3次了吗：" + Repeat3(p2, 1));
    Interaction.MsgBox("12出现3次了吗：" + Repeat3(p2, 12));
}
protected internal bool Repeat3(Dictionary<int, int> dictionary, int number)
{
    if (dictionary.ContainsKey(number)) {
        return (dictionary[number] > 2);
    } else {
        return false;
    }
}
protected internal void Add(Dictionary<int, int> dictionary, int number)
{
    if (dictionary.ContainsKey(number)) {
        dictionary[number] += 1;
    } else {
        dictionary[number] = 1;
    }
}

------解决方案--------------------
C# code
var last6 = list.Skip(list.Count - 6).ToList();
if (last.Select((x, i) => new { x, i }).All(x => (x.i % 2 == 0 || x.x == 12) && (x.i %2 == 1 || x.x == 11)))
{
    ...
}

------解决方案--------------------
C# code
bool b=!p2.Where(p=>new int[]{11,12}.Contains(p)).GroupBy(p=>p).All(g=>g.Count()>=3);

------解决方案--------------------
bool b=!p2.Where(p=>new int[]{11,12}.Contains(p)).GroupBy(p=>p).All(g=>g.Count()>=3);

------解决方案--------------------
如果仅仅是判断，可以简单点，如下：
List<int> p2 = new List<int>(); // TODO: 初始化为适当的值
           p2.Add(1);
           p2.Add(2);
           p2.Add(3);
           p2.Add(4);
           p2.Add(5);
           p2.Add(6);
           p2.Add(13);
           p2.Add(12);
           p2.Add(11);
           p2.Add(12);
           p2.Add(11);
           p2.Add(12);
           p2.Add(11);
           p2.Add(12);
           string str="";
           foreach (int i in p2)
               str += i.ToString();
           if (Regex.IsMatch(str, @"(1112){3,}"))
               MessageBox.Show("重复三次");

------解决方案--------------------
原来我理解错了啊

------解决方案--------------------
C# code

protected internal void S()
{
    List<int> p2 = new List<int>();
    p2.Add(1);
    p2.Add(2);
    p2.Add(3);
    p2.Add(4);
    p2.Add(5);
    p2.Add(6);
    p2.Add(13);
    p2.Add(12);
    p2.Add(11);
    p2.Add(12);
    p2.Add(11);
    p2.Add(12);
    p2.Add(11);
    p2.Add(12);
    Interaction.MsgBox("[,11,,12,]:" + Repeat3(p2, ",11,,12,"));
    Interaction.MsgBox("[,11,,3,]:" + Repeat3(p2, ",11,,3,"));
}

protected internal bool Repeat3(List<int> p2, string numbers)
{
    StringBui