求List<int>中相等且连续的偶数的索引

比如 {3,5,4,4,4,3,6,6,5} 结果是：{2,3,4,6,7}

using System;
using System.Text;
using System.Collections.Generic;

namespace CSharpProject
{
    class Program
    {
        static void Main(string[] args)
        {
            List<int> list = new List<int>() { 0, 0, 3, 5, 4, 4, 4, 3, 6, 6, 5, 8, 8 };
            StringBuilder sb = new StringBuilder();
            GetCloseEqualityEvenNumIndexFromList(list, ref sb);
            Console.WriteLine(sb.ToString());

            Console.ReadKey();
        }

        //计算List<int>中相等且连续的偶数的索引 比如 {3,5,4,4,4,3,6,6,5} 结果是：{2,3,4,6,7}
        static void GetCloseEqualityEvenNumIndexFromList(List<int> list, ref StringBuilder sb)
        {
            if (null == sb)
                sb = new StringBuilder();

            if (null != list)
            {
                int i = 0, iMax = 0, index = 0, counter = 0;
                int currVal = 0, nextVal = 0;
                sb.Append("{");
                for (i = 0, iMax = list.Count; i < iMax; i += (counter + 1))
                {
                    currVal = list[i];
                    counter = 0;
                    for (index = i + 1; index < iMax; ++index)
                    {
                        nextVal = list[index];
                        if (currVal == nextVal && currVal % 2 == 0 && nextVal % 2 == 0)
                        {
                            ++counter;
                            if (index - i <= 1)
                                sb.Append(i.ToString() + ",");
                            sb.Append((i + counter).ToString() + ",");
                        }
                        else
                        {
                            break;
                        }
                    }
                }
                sb.Remove(sb.Length - 1, 1);
                sb.Append("}");
            }
        }
    }
}

结果: