一个字符串中暴力的找出一个出现频率最高的字符

 private string teststr(string temp)
    {     
        int maxCount = 0;
        string res = String.Empty;
        while (temp.Length>0)
        {
            string ts = temp.Substring(0, 1);
            int count = temp.Length;
            temp = temp.Replace(ts, "");
            count = count - temp.Length;
            if (maxCount < count)
            {
                res = ts;
                maxCount = count;
            }
        }
        return res;      
    }
  var s = teststr("4121111421421341234");

暴力的很。。。。