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  3. Friday Programming Quiz [modified]

Friday Programming Quiz [modified]

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  • R Rama Krishna Vavilala

    There are some number of text files. Each file contains a number separated by a comma and a name. e.g. File 1

    1,Chris Maunder
    20248,Nishant Sivakumar
    36803,Marc Clifton
    ...

    File 2

    6556,Christian Graus
    7741,John Simmons / outlaw programmer
    15383,Rama Krishna Vavilala
    ...

    All the records in the file are sorted by the id (the number). Note there can be many such files. The purpose is to generate a new file like this:

    1,Chris Maunder
    6556,Christian Graus
    7741,John Simmons / outlaw programmer
    15383,Rama Krishna Vavilala
    20248,Nishant Sivakumar
    36803,Marc Clifton
    ...

    Of course it can be done in a programming language of your choice. I might be able to hand over a prize for the most innovative and interesting/ solution.;) -- modified at 15:01 Friday 24th August, 2007

    Co-Author ASP.NET AJAX in Action

    L Offline
    L Offline
    lost in transition
    wrote on last edited by
    #30

    I would like to see someone right a solution in QBasic:) or Pascal:rose:. Make you own front end. Will this work.

    namespace CP
    {
    static class Program
    {
    /// /// The main entry point for the application.
    ///
    [STAThread]
    static void Main()
    {
    PQuizOTD pqtd = new PQuizOTD();
    pqtd.ReadFile(@"C:\TestData1.txt");
    pqtd.ReadFile(@"C:\TestData2.txt");
    pqtd.ExportToFile();
    }
    }
    class PQuizOTD
    {
    private DataTable dt;

        public PQuizOTD()
        {
            dt = new DataTable();
            dt.Columns.AddRange(
                        new DataColumn\[\] { 
                            new DataColumn("ID"), 
                            new DataColumn("Name") });
        }
    
        public void ReadFile(string FileName)
        {
            string line;
            StreamReader sr = new StreamReader(FileName);
            while (!sr.EndOfStream)
            {
                line = sr.ReadLine();
                int index = line.IndexOf(",");
                DataRow dr = dt.NewRow();
                dr\[0\] = line.Substring(0, index);
                dr\[1\] = line.Substring(index + 1, (line.Length - index - 1));
                dt.Rows.Add(dr);
            }
        }
    
        public void ExportToFile()
        {
            dt.DefaultView.Sort = "Name ASC";
            dt.AcceptChanges();
            dt = dt.DefaultView.ToTable();
            StreamWriter sw = new StreamWriter(@"C:\\TestData\_Export.txt");
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                sw.WriteLine(dt.Rows\[i\]\[0\].ToString() + "," + dt.Rows\[i\]\[1\].ToString());
            }
            sw.Close();
        }
    }
    

    }


    God Bless, Jason
    God doesn't believe in atheist but He still loves them.

    1 Reply Last reply
    0
    • R Rama Krishna Vavilala

      There are some number of text files. Each file contains a number separated by a comma and a name. e.g. File 1

      1,Chris Maunder
      20248,Nishant Sivakumar
      36803,Marc Clifton
      ...

      File 2

      6556,Christian Graus
      7741,John Simmons / outlaw programmer
      15383,Rama Krishna Vavilala
      ...

      All the records in the file are sorted by the id (the number). Note there can be many such files. The purpose is to generate a new file like this:

      1,Chris Maunder
      6556,Christian Graus
      7741,John Simmons / outlaw programmer
      15383,Rama Krishna Vavilala
      20248,Nishant Sivakumar
      36803,Marc Clifton
      ...

      Of course it can be done in a programming language of your choice. I might be able to hand over a prize for the most innovative and interesting/ solution.;) -- modified at 15:01 Friday 24th August, 2007

      Co-Author ASP.NET AJAX in Action

      D Offline
      D Offline
      David Crow
      wrote on last edited by
      #31

      Looks like a job for merge sort.


      "A good athlete is the result of a good and worthy opponent." - David Crow

      "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

      D 1 Reply Last reply
      0
      • P PIEBALDconsult

        type *.in | sort > CP.out Unless, by "(the number)", you mean "the numerical value of the id".

        D Offline
        D Offline
        David Crow
        wrote on last edited by
        #32

        Are you sure that TYPE works with wildcards?


        "A good athlete is the result of a good and worthy opponent." - David Crow

        "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

        P 1 Reply Last reply
        0
        • T Tarakeshwar Reddy

          Dictionary<int, string> cpians = new Dictionary<int, string>();
          List<int> keylist = new List<int>();

          string strLine = "";

          foreach (System.IO.FileInfo fi in new System.IO.DirectoryInfo(@"C:\quiz\").GetFiles())
          {              
              using (System.IO.StreamReader sr = fi.OpenText())
              {
                  while (sr.Peek() >= 0)
                  {
                      strLine = sr.ReadLine();
                      cpians.Add(Int32.Parse(strLine.Split(',')[0]), strLine.Split(',')[1]);
                      keylist.Add(Int32.Parse(strLine.Split(',')[0]));
                  }
              }
          }

          keylist.Sort();

          using (System.IO.FileStream file = new System.IO.FileStream(@"C:\TotalList.txt", System.IO.FileMode.Create, System.IO.FileAccess.Write))
          {
              using (System.IO.StreamWriter sw = new System.IO.StreamWriter(file))
              {
                  foreach (int key in keylist)
                  {
                      sw.WriteLine(key + "," + cpians[key]);
                  }
              }
          }

          The items in the file need not be sorted for this solution.

          T Offline
          T Offline
          Tarakeshwar Reddy
          wrote on last edited by
          #33

          Modified version using SortedList<>.

          SortedList<int, string> cpians = new SortedList<int, string>();                       
          string strLine = "";

          foreach (System.IO.FileInfo fi in new System.IO.DirectoryInfo(@"C:\quiz\").GetFiles())
          {
              using (System.IO.StreamReader sr = fi.OpenText())
              {
                  while (sr.Peek() >= 0)
                  {
                      strLine = sr.ReadLine();
                      cpians.Add(Int32.Parse(strLine.Split(',')[0]), strLine.Split(',')[1]);                       
                  }
              }
          }

          using (System.IO.FileStream file = new System.IO.FileStream(@"C:\TotalList.txt", System.IO.FileMode.Create, System.IO.FileAccess.Write))
          {
              using (System.IO.StreamWriter sw = new System.IO.StreamWriter(file))
              {
                  foreach (KeyValuePair<int, string> kvp in cpians)
                  {
                      sw.WriteLine(kvp.Key + "," + kvp.Value);
                  }
              }
          }

          R 1 Reply Last reply
          0
          • D David Crow

            Looks like a job for merge sort.


            "A good athlete is the result of a good and worthy opponent." - David Crow

            "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

            D Offline
            D Offline
            Daniel Grunwald
            wrote on last edited by
            #34

            Take a look at my "on-the-fly" solution for a merge sort solution that requires memory only linear to the number of files, independent from the file size.

            1 Reply Last reply
            0
            • J Jim Crafton

              "Computer" I shout. "Yes Master?" "Create a file for me!" "All right. What do you want in the file?" "Names, and an ID number. Can you do that brainiac?" "Cut the crap Boss. Sure thing. Anything else?" "Yeah, keep the file sorted by ID, in ascending order." "Fine. Done. Where do I get the names from?" "They are in another file, it's text, and comma delimited. The first thing on a line is a number, the ID, followed by a name." "Are there multiple entries in a file?" "Yep." "OK, ready to rock and roll."

              ¡El diablo está en mis pantalones! ¡Mire, mire! Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)! SELECT * FROM User WHERE Clue > 0 0 rows returned Save an Orange - Use the VCF! VCF Blog

              M Offline
              M Offline
              martin_hughes
              wrote on last edited by
              #35

              I think I need to adopt this style of programming :)

              "It was the day before today.... I remember it like it was yesterday." -Moleman

              1 Reply Last reply
              0
              • P PIEBALDconsult

                Oh, now that's got me thinking of Douglas Adams again, Dirk Gently in fact: The program kgvclsg lgzszsil gvhzxido;vzxdl'vcbx gcb ;klh gjl;ghilsfdghb kZG l gh will perform the task, we just need to find a compiler for it! :laugh:

                M Offline
                M Offline
                martin_hughes
                wrote on last edited by
                #36

                Surely you'd only get a suffusion of yellow given the inputs?

                "It was the day before today.... I remember it like it was yesterday." -Moleman

                1 Reply Last reply
                0
                • T Tarakeshwar Reddy

                  Modified version using SortedList<>.

                  SortedList<int, string> cpians = new SortedList<int, string>();                       
                  string strLine = "";

                  foreach (System.IO.FileInfo fi in new System.IO.DirectoryInfo(@"C:\quiz\").GetFiles())
                  {
                      using (System.IO.StreamReader sr = fi.OpenText())
                      {
                          while (sr.Peek() >= 0)
                          {
                              strLine = sr.ReadLine();
                              cpians.Add(Int32.Parse(strLine.Split(',')[0]), strLine.Split(',')[1]);                       
                          }
                      }
                  }

                  using (System.IO.FileStream file = new System.IO.FileStream(@"C:\TotalList.txt", System.IO.FileMode.Create, System.IO.FileAccess.Write))
                  {
                      using (System.IO.StreamWriter sw = new System.IO.StreamWriter(file))
                      {
                          foreach (KeyValuePair<int, string> kvp in cpians)
                          {
                              sw.WriteLine(kvp.Key + "," + kvp.Value);
                          }
                      }
                  }

                  R Offline
                  R Offline
                  Rama Krishna Vavilala
                  wrote on last edited by
                  #37

                  Infact you don't even need fi.OpenText. You can directly supply the file names to the StreamReader and StreamWriter.

                  Co-Author ASP.NET AJAX in Action

                  T 1 Reply Last reply
                  0
                  • D David Crow

                    Are you sure that TYPE works with wildcards?


                    "A good athlete is the result of a good and worthy opponent." - David Crow

                    "To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

                    P Offline
                    P Offline
                    PIEBALDconsult
                    wrote on last edited by
                    #38

                    Yes, it works.

                    1 Reply Last reply
                    0
                    • R Rama Krishna Vavilala

                      Infact you don't even need fi.OpenText. You can directly supply the file names to the StreamReader and StreamWriter.

                      Co-Author ASP.NET AJAX in Action

                      T Offline
                      T Offline
                      Tarakeshwar Reddy
                      wrote on last edited by
                      #39

                      Oh yeah, for the StreamWriter, I could have directly given the filename :doh:. In the StreamReader, I use FileInfo to get a list of files in the particular directory, since I have it declared I am using fi.OpenText() which returns to me a StreamReader

                      1 Reply Last reply
                      0
                      • D Daniel Grunwald

                        My first solution requires loading everything into memory (ReadAllLines/WriteAllLines uses arrays, OrderBy requires having the whole list in memory). Here is another LINQ solution that uses a custom functions for reading/writing files and merging the enumerables:

                        using System;
                        using System.IO;
                        using System.Collections.Generic;
                        using System.Linq;
                        static class Program {
                        public static void Main(string[] args) {
                        SortedMerge(args.Select(
                        fileName => FileReadLines(fileName).Select(
                        line => new { ID = int.Parse(line.Split(',')[0]), Name = line.Split(',')[1]}
                        )), a=>a.ID)
                        .Select(a=>string.Format("{0},{1}", a.ID, a.Name))
                        .WriteToFile("output.txt");
                        }

                        static IEnumerable<string> FileReadLines(string fileName)
                        {
                        	using (StreamReader reader = new StreamReader(fileName)) {
                        		string line;
                        		while ((line = reader.ReadLine()) != null) {
                        			Console.WriteLine("read " + line + " from " + fileName);
                        			yield return line;
                        		}
                        	}
                        }
                        
                        static void WriteToFile(this IEnumerable<string> lines, string fileName)
                        {
                        	using (StreamWriter writer = new StreamWriter(fileName)) {
                        		foreach (string line in lines) {
                        			Console.WriteLine("write " + line + " to " + fileName);
                        			writer.WriteLine(line);
                        		}
                        	}
                        }
                        
                        static IEnumerable<T> SortedMerge<T, K>(IEnumerable<IEnumerable<T>> inputs, Func<T, K> keySelector) where K : IComparable<K>
                        {
                        	var enumerators = inputs.Select(o=>o.GetEnumerator()).ToList();
                        	var disposables = enumerators.ToList(); // make copy of enumerators for disposing them later
                        	try {
                        		// move all enumerators on the first element
                        		enumerators.RemoveAll(e=>!e.MoveNext());
                        		while (enumerators.Count > 0) {
                        			int smallest = 0;
                        			for (int i = 1; i < enumerators.Count; i++) {
                        				// the the element of the current enumerator smaller than the best found so far?
                        				if (keySelector(enumerators\[i\].Current).CompareTo(keySelector(enumerators\[smallest\].Current)) < 0) {
                        					smallest = i;
                        				}
                        			}
                        			yield return enumerators\[smallest\].Current;
                        			if (!enumerators\[smallest\].MoveNext())
                        				enumerators.RemoveAt(smallest);
                        		}
                        	} finally {
                        		disposables.ForEach(d => d.Dispose());
                        	}
                        }
                        

                        }

                        The debug output shows that the program is writing as soon as possible; written lines will be collected by the GC, so this solution can merge multi-GB files without running out of memory. Output:

                        C:\temp\SharpDevelop Projects\CPQ

                        R Offline
                        R Offline
                        Rama Krishna Vavilala
                        wrote on last edited by
                        #40

                        I guess you are the winner. Will you like a copy of ASP.NET AJAX in Action?

                        Co-Author ASP.NET AJAX in Action

                        1 Reply Last reply
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                        • C Chris Meech

                          Rama Krishna Vavilala wrote:

                          Of course it can be done in language of your choice

                          Give a couple of hours and I'll have the COBOL version slapped together for you. :)

                          Chris Meech I am Canadian. [heard in a local bar]

                          A Offline
                          A Offline
                          Anthony Potts
                          wrote on last edited by
                          #41

                          that's not funny, I mainly do COBOL. It makes me sad to think about how this would be done in COBOL.

                          "If you really want something in this life, you have to work for it. Now, quiet! They're about to announce the lottery numbers..." - Homer Simpson

                          1 Reply Last reply
                          0
                          • J Jim Crafton

                            "Computer" I shout. "Yes Master?" "Create a file for me!" "All right. What do you want in the file?" "Names, and an ID number. Can you do that brainiac?" "Cut the crap Boss. Sure thing. Anything else?" "Yeah, keep the file sorted by ID, in ascending order." "Fine. Done. Where do I get the names from?" "They are in another file, it's text, and comma delimited. The first thing on a line is a number, the ID, followed by a name." "Are there multiple entries in a file?" "Yep." "OK, ready to rock and roll."

                            ¡El diablo está en mis pantalones! ¡Mire, mire! Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)! SELECT * FROM User WHERE Clue > 0 0 rows returned Save an Orange - Use the VCF! VCF Blog

                            P Offline
                            P Offline
                            PIEBALDconsult
                            wrote on last edited by
                            #42

                            Picard: "Data, do something with these files."

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