Friday Programming Quiz [modified]

Rama Krishna Vavilala

No your solution is correct! There will be no duplicates.

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:

Luis Alonso Ramos

I need to start learning LINQ :doh: I'll give you a 5 and suppose that it actually works :)

Luis Alonso Ramos Intelectix Chihuahua, Mexico

My Blog!

PIEBALDconsult

OK, then my version of sort does. :-D

Gary Wheeler

Watch it; remember the kid-sister rule in the Lounge.

Software Zen: delete this;

Minosknight

precisely, I was just being lame and put the desired end result into a text to binary converter. I suppose you could just do it the other way around and TAH-DAH!;P

Think of it this way...using a Stradivarius violin to pound nails should not be considered a sound construction technique

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

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.

PIEBALDconsult

string inline ;

System.Collections.Generic.List list =
new System.Collections.Generic.List() ;

while ( ( inline = System.Console.ReadLine() ) != null )
{
list.Add ( inline.PadLeft ( inline.Length + 16 - inline.IndexOf ( ',' ) , ' ' ) ) ;
}

list.Sort() ;

foreach ( string s in list )
{
System.Console.WriteLine ( s.TrimStart() ) ;
}

lost in transition

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.

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

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

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);
        }
    }
}

Daniel Grunwald

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.

martin_hughes

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

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

martin_hughes

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

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

PIEBALDconsult

Yes, it works.

Tarakeshwar Reddy

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

Rama Krishna Vavilala

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

Co-Author ASP.NET AJAX in Action