using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Text;

public class Program

{

    public static void Main()

    {

        var lines_list = new List<string>();

        var wordsArr = new string[]{"alpha", "beta", "gama", "delta", "Epsilon", "Zeta", "Eta", "Theta", "Iota", "kaPPa", "LamBda", "mU", "Nu", "xi", "omicron", "pi", "rHo", "siGma", "Tau", "UpSiLoN", "pHi", "chi", "psi", "omega"};

        var ss = new StringBuilder();

        var rnd = new Random( 12345 );      

        for ( int i = 0; i < 50000; i++ )

        {            

             var words_arr = new List<string>();

             for ( int j = 0; j < rnd.Next(10,20); j++)

             {

                words_arr.Add( wordsArr[ rnd.Next( wordsArr.Length ) ] );            

             }

             var tab_count = rnd.Next( 0, 5 );

             var line = new StringBuilder();

             if ( i % 17 == 0 )

             {

                 line.Append("\t\n");

             }

             else

             {

                if ( i % 33 == 0 )

                 {

                     line.Append("\n");

                 }

                else

                {

                    for ( int k = 0; k < tab_count; k++ ) line.Append("\t");                    

                    foreach( var w in words_arr ) 

                    {

                        line.Append( " " + w );

                    }                   

                }

             }

            var result = line + "\n";

            ss.Append( result );

            lines_list.Add( result );

​

        }

    var sw = new System.Diagnostics.Stopwatch();

    sw.Start();

    var tp = new TextProcessor();

    tp.ProcessFile( lines_list.ToArray(), new string[]{ "alpha", "beta", "gama", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa", "lambda", "mu", "nu", "xi", "omicron", "pi", "rho", "sigma", "tau", "upsilon", "phi", "chi", "psi", "omega"});

    Console.WriteLine( "--> Time: " + sw.ElapsedMilliseconds + " ms. ") ;

    //Console.WriteLine( tp.keys );

    //Console.WriteLine( tp.lines[5] );

    }

}

​

​

    /*

    foreach( var k in tp.keys )

    {

        Console.WriteLine( $"'{k}' { tp.data[ k ].count }  lines:{ tp.data[ k ].lines.Count }  indexes:{ tp.data[ k ].indexes.Count}"); 

    }

    */

​

​

// Define other methods and classes here

        public class Line

        {

            public int count = 0;

            public List<string> lines;

            public List<int> indexes;

            public Line()

            {

                count = 0;

                lines   = new List<string>(){};

                indexes = new List<int>();

            }

            public Line( string line, int index )

            {

                count   = 1;

                lines   = new List<string>(){ line };

                indexes = new List<int>(){ index };

            }

            public void AddLine( string line, int index )

            {

                lines.Add( line );

                indexes.Add( index );

                count++;

            }

        }

​

        public class TextProcessor

        {

            public Dictionary<string, Line> data;

            public string[] keys;

            public Line[] lines;

            public void ProcessFile(string[] lines, string[] words)

            {   

                data = new Dictionary<string, Line>();

                //foreach( var w in words) data[w] = new Line();

                var spaces = new char[]{' ','   ','\r','\n'};

                //string[] lines = File.ReadAllLines(file);

                if (lines != null)

                {

                    int line_index = 0;

                    string word;

                    foreach(string line in lines)

                    {

                        line_index++;

                        // #1

                        //word = line.TrimStart(spaces).Split()[0].ToLower();

                        // #1.5

                        //word = line.Trim().Split(null, 2)[0].ToLower();

                        // #2

                        //word = line.TrimStart(spaces);

                        //int len  = word.IndexOfAny( spaces );

                        //word = word.Substring( 0, len < 0 ? word.Length : len ).ToLower();

                        // #3

                        //var chars = line.ToCharArray();                       

                        //int f1 = Array.FindIndex(chars,     x => !char.IsWhiteSpace(x));                      

                        //if ( f1 < 0 ) continue;                       

                        //int f2 = Array.FindIndex(chars, f1, x => char.IsWhiteSpace(x));

                        //word = line.Substring( f1, f2 - f1 ).ToLower();

                        // #4                       

                        int f1 = -1;

                        for ( int i = 0; i < line.Length; i++ )

                        {

                            if ( !char.IsWhiteSpace(line[i]) )

                            {

                                f1 = i;

                                break;

                            }

                        }

                        if ( f1 < 0 ) continue;

                        int f2 = line.Length;

                        for ( int i = f1; i < line.Length; i++ )

                        {

                            if ( char.IsWhiteSpace(line[i]) )

                            {

                                f2 = i;

                                break;

                            }

                        }

                        word = line.Substring( f1, f2 - f1 ).ToLower();

                        if (data.ContainsKey(word))

                        {

                            data[word].AddLine( line, line_index );                         

                        }

                        else

                        {

                            data[word] = new Line( line, line_index );                          

                        }

                    }

                }

                keys = new string[data.Keys.Count];

                data.Keys.CopyTo(keys, 0);              

                this.lines = new Line[data.Values.Count];

                data.Values.CopyTo(this.lines, 0);

            }

        }