???????????????????????????ShortenUrl??
????using System;
????using System.Linq;
????using System.Web;
????using System.IO;
????using System.Text;
????/// <summary>
????/// ShortenUrl ???????
????/// </summary>
????public class ShortenUrl
????{
????const string Seq = "s9LFkgy5RovixI1aOf8UhdY3r4DMplQZJXPqebE0WSjBn7wVzmN2Gc6THCAKut";
????private static string DataFile
????{
????get { return HttpContext.Current.Server.MapPath("/Url.db"); }
????}
????private static string IndexFile
????{
????get { return HttpContext.Current.Server.MapPath("/Url.idx"); }
????}
????/// <summary>
????/// ???????????????????Key???????????????????в??????????????????????λ????±????????null??
????/// </summary>
????/// <param name="Url"></param>   
????/// <returns></returns>
????public static string[] AddUrl(string[] Url)
????{
????FileStream Index = new FileStream(IndexFile?? FileMode.OpenOrCreate?? FileAccess.ReadWrite);
????FileStream Data = new FileStream(DataFile?? FileMode.Append?? FileAccess.Write);
????Data.Position = Data.Length;
????DateTime Now = DateTime.Now;
????byte[] dt = BitConverter.GetBytes(Now.ToBinary());
????int _Hits = 0;
????byte[] Hits = BitConverter.GetBytes(_Hits);
????string[] ResultKey = new string[Url.Length];
????int seekSeek = unchecked((int)Now.Ticks);
????Random seekRand = new Random(seekSeek);
????string Host = HttpContext.Current.Request.Url.Host.ToLower();       
????byte[] Status = BitConverter.GetBytes(true);
????//index: ID(8) + Begin(8) + Length(2) + Hits(4) + DateTime(8) = 30
????for (int i = 0; i < Url.Length && i<1000; i++)
????{
????if (Url[i].ToLower().Contains(Host) || Url[i].Length ==0 ||  Url[i].Length > 4096) continue;
????long Begin = Data.Position;           
????byte[] UrlData = Encoding.UTF8.GetBytes(Url[i]);           
????Data.Write(UrlData?? 0?? UrlData.Length);                       
????byte[] buff = new byte[8];
????long Last;
????if (Index.Length >= 30) //?????????????ID
????{
????Index.Position = Index.Length - 30;
????Index.Read(buff?? 0?? 8);
????Index.Position += 22;
????Last = BitConverter.ToInt64(buff?? 0);
????}
????else
????{
????Last = 1000000; //??ID??????С?????????????????
????Index.Position = 0;
????}
????long RandKey = Last + (long)GetRnd(seekRand);
????byte[] BeginData = BitConverter.GetBytes(Begin);
????byte[] LengthData = BitConverter.GetBytes((Int16)(UrlData.Length));
????byte[] RandKeyData = BitConverter.GetBytes(RandKey);
????Index.Write(RandKeyData?? 0?? 8);
????Index.Write(BeginData?? 0?? 8);
????Index.Write(LengthData?? 0?? 2);
????Index.Write(Hits?? 0?? Hits.Length);           
????Index.Write(dt?? 0?? dt.Length);           
????ResultKey[i] = Mixup(RandKey);
????}
????Data.Close();
????Index.Close();
????return ResultKey;
????}
????/// <summary>
????/// ?????????????Key????????鳤?????
????/// </summary>
????/// <param name="Key"></param>
????/// <returns></returns>
????public static string[] ParseUrl(string[] Key)
????{
????FileStream Index = new FileStream(IndexFile?? FileMode.OpenOrCreate?? FileAccess.ReadWrite);
????FileStream Data = new FileStream(DataFile?? FileMode.Open?? FileAccess.Read);       
????byte[] buff = new byte[8];
????long[] Ids = Key.Select(n => UnMixup(n)).ToArray();
????string[] Result = new string[Ids.Length];
????long _Right = (long)(Index.Length / 30) - 1;       
????for (int j = 0; j < Ids.Length; j++)
????{
????long Id = Ids[j];           
????long Left = 0;
????long Right = _Right;
????long Middle = -1;           
????while (Left <= Right)
????{
????Middle = (long)(Math.Floor((double)((Right + Left) / 2)));
????if (Middle < 0) break;
????Index.Position = Middle * 30;
????Index.Read(buff?? 0?? 8);
????long val = BitConverter.ToInt64(buff?? 0);
????if (val == Id) break;               
????if (val < Id)
????{
????Left = Middle + 1;
????}
????else
????{
????Right = Middle - 1;
????}
????}           
????string Url = null;
????if (Middle != -1)
????{
????Index.Position = Middle * 30 + 8; //????ID          
????Index.Read(buff?? 0?? buff.Length);
????long Begin = BitConverter.ToInt64(buff?? 0);
????Index.Read(buff?? 0?? buff.Length);
????Int16 Length = BitConverter.ToInt16(buff?? 0);
????byte[] UrlTxt = new byte[Length];
????Data.Position = Begin;
????Data.Read(UrlTxt?? 0?? UrlTxt.Length);
????int Hits = BitConverter.ToInt32(buff?? 2);//????2????Length
????byte[] NewHits = BitConverter.GetBytes(Hits + 1);//?????????????? 4???
????Index.Position -= 6;//??????Length???
????Index.Write(NewHits?? 0?? NewHits.Length);//???????Hits
????Url = Encoding.UTF8.GetString(UrlTxt);                      
????}
????Result[j] = Url;
????}       
????Data.Close();
????Index.Close();
????return Result;
????}
????/// <summary>
????/// ????id??????
????/// </summary>
????/// <param name="id"></param>
????/// <returns></returns>
????private static string Mixup(long id)
????{
????string Key = Convert(id);
????int s = 0;
????foreach (char c in Key)
????{
????s += (int)c;
????}
????int Len = Key.Length;
????int x = (s % Len);
????char[] arr = Key.ToCharArray();
????char[] newarr = new char[arr.Length];
????Array.Copy(arr?? x?? newarr?? 0?? Len - x);
????Array.Copy(arr?? 0?? newarr?? Len - x?? x);
????string NewKey = "";
????foreach (char c in newarr)
????{
????NewKey += c;
????}
????return NewKey;
????}
????/// <summary>
????/// ???????????
????/// </summary>
????/// <param name="Key"></param>
????/// <returns></returns>
????private static long UnMixup(string Key)
????{
????int s = 0;
????foreach (char c in Key)
????{
????s += (int)c;
????}
????int Len = Key.Length;
????int x = (s % Len);
????x = Len - x;
????char[] arr = Key.ToCharArray();
????char[] newarr = new char[arr.Length];
????Array.Copy(arr?? x?? newarr?? 0?? Len - x);
????Array.Copy(arr?? 0?? newarr?? Len - x?? x);
????string NewKey = "";       
????foreach (char c in newarr)
????{
????NewKey += c;
????}
????return Convert(NewKey);
????}
????/// <summary>
????/// 10????????62????
????/// </summary>
????/// <param name="id"></param>
????/// <returns></returns>
????private static string Convert(long id)
????{
????if (id < 62)
????{
????return Seq[(int)id].ToString();
????}
????int y = (int)(id % 62);
????long x = (long)(id / 62);
????return Convert(x) + Seq[y];
????}
????/// <summary>
????/// ??62??????10????
????/// </summary>
????/// <param name="Num"></param>
????/// <returns></returns>
????private static long Convert(string Num)
????{
????long v = 0;
????int Len = Num.Length;
????for (int i = Len - 1; i >= 0; i--)
????{
????int t = Seq.IndexOf(Num[i]);
????double s = (Len - i) - 1;
????long m = (long)(Math.Pow(62?? s) * t);
????v += m;
????}
????return v;
????}
????/// <summary>
????/// ?????????0-9a-zA-Z?????
????/// </summary>
????/// <returns></returns>
????public static string GenerateKeys()
????{
????string[] Chars = "0??1??2??3??4??5??6??7??8??9??A??B??C??D??E??F??G??H??I??J??K??L??M??N??O??P??Q??R??S??T??U??V??W??X??Y??Z??a??b??c??d??e??f??g??h??i??j??k??l??m??n??o??p??q??r??s??t??u??v??w??x??y??z".Split('??');
????int SeekSeek = unchecked((int)DateTime.Now.Ticks);
????Random SeekRand = new Random(SeekSeek);
????for (int i = 0; i < 100000; i++)
????{
????int r = SeekRand.Next(1?? Chars.Length);
????string f = Chars[0];
????Chars[0] = Chars[r - 1];
????Chars[r - 1] = f;
????}
????return string.Join(""?? Chars);
????}
????/// <summary>
????/// ???????????????
????/// </summary>
????/// <param name="SeekRand"></param>
????/// <returns></returns>
????private static Int16 GetRnd(Random SeekRand)
????{
????Int16 Step = (Int16)SeekRand.Next(1?? 11);
????return Step;
????}
????}
???????????????
??????10?????ID????62??????????6λ????62???????????? 62^6??568??????????????????1~10????????5????6λ??????????????????113.6??????????????????????????????????????????????????????????Append???д?????д?????????????????????????????????????????????????????8??????棬??????????????
???????????????????￡??????????????????IO????????????????Node.js????????????????????????