Programming Game #1

Bored, time for a small programming game. Here it is, plain and simple. I tell you a function you have to write (and what must be done in that function), and whoever can code it in the smallest amount of characters wins. It will teach you to optimize your code, although you might have to use some abhorred programming techniques along the way.

You can use any language.

Not limited to one entry per person. If someone beats you, go back to your code and try and make it smaller. Once nobody can beat it anymore, game over.

Prize: 50k LG to winner.

Function you have to make
Return a list of all prime numbers between a lower limit and upper limit.

Function must:
- be named Primes.
- not return 1 as a prime number (i.e. if 1 is entered as lower limit, 2 will be the first prime).
- return null result if upper limit lower than lower limit.

Rules:
- spaces not included in total character length (new lines don't count as well)
- don't just use someone elses code and optimize it. Use your own code.


My entry (coded in PHP)

function Primes($l, $u)

{

	if($l <= 1) $l = 2;

	if($u <= $l) return;



	for($x = $l; $x <= $u; $x++)

		$z[] = $x;



	for($i = 0; $c*$c < $u; $i++)

	{

		$c = $z[$i];

		foreach($z as $d => $v)

			if($v % $c == 0 && $v != $c)

				unset($z[$d]);



		$z = array_values($z);

	}



	return $z;

}

Char length: 201.

[i]print_r(Primes(0,30));[/i] returns:



Array

(

    [0] => 2

    [1] => 3

    [2] => 5

    [3] => 7

    [4] => 11

    [5] => 13

    [6] => 17

    [7] => 19

    [8] => 23

    [9] => 29

)

[/9][/8][/7][/6][/5][/4][/3][/2][/1][/0]

  function Primes($l, $u)

{

    if($l <= 1) $l = 2;

    if($u <= $l) return;



    for($x = $l; $x <= $u; $x++)

        $z[] = $x;



    for($i = 0; $c*$c < $u; $i++)

    {

        $c = $z[$i];

        foreach($z as $d => $v)

            if($v % $c == 0 && $v != $c)

                unset($z[$d]);



        $z = array_value($z);

    }



    return $z;

}  

200 chars.

Mine:

def Primes(l,u,p):

    if l<2:

        l=2

    if u<2:

        return

    u+=1

    for i in range(l,u):

        f=True

        for x in range(l,u):

            if i%x==0 and i!=x and i>x:

                f=False

        if f:

            p.append(i)

    return p

Output:

>>> p = Primes(0,30,[])

>>> for i in p:

	print(i)



	

2

3

5

7

11

13

17

19

23

29

>>> 

Characters (without \n and spaces): 133

No precoded functions, right? Java (Lame, I know, but all I remember right now xD) has a prime checking function that I could just run numbers through.

;D Woo. Something i can participate in >.< -Makin mine in C, give me 15 mins or soo-

EDIT:: =.= getting caught up in something, ill have to do it later.

What's the time limit?

Smithno13 wrote:

No precoded functions, right? Java (Lame, I know, but all I remember right now xD) has a prime checking function that I could just run numbers through.

I know I said all languages, but that's too easy for sure. Riddle is in the lead, time to go change mine up.

Yea, I figured not. I really need to learn more coding languages but I have never really had need or inspiration to do so.

Riddle wrote:

Mine:

def Primes(l,u,p):

    if l<2:

        l=2

    if u<2:

        return

    u+=1

    for i in range(l,u):

        f=True

        for x in range(l,u):

            if i%x==0 and i!=x and i>x:

                f=False

        if f:

            p.append(i)

    return p

Output:

>>> p = Primes(0,30,[])

>>> for i in p:

	print(i)



	

2

3

5

7

11

13

17

19

23

29

>>> 

Characters (without \n and spaces): 133

Pardon my nubness, what language is that?

It's python.

I only managed to shorten mine down by an additional 30 characters <.< I'll have another go later, and if unable to may swap language. Python is such a simple language, not sure I'll be able to.

function Primes($l, $u)

{

	if($l < 2) $l = 2;

	if($u < 2) return;



	$z = range($l,$u);

	foreach($z as $i => $c)

		foreach($z as $d => $v)

			if($v % $c == 0 && $v != $c) 

				unset($z[$d]);

			else $a[$i][] = $z[$d];



	return $a[$i];

}

Program:
MEGAUPLOAD - Primes.rar

Source:

Imports System.ComponentModel



Public Class Primes

    Private backgroundCalculator As System.ComponentModel.BackgroundWorker



    Public Sub New()



        InitializeComponent()



        backgroundCalculator = New BackgroundWorker()

        backgroundCalculator.WorkerReportsProgress = True

        backgroundCalculator.WorkerSupportsCancellation = True



        AddHandler backgroundCalculator.DoWork, New DoWorkEventHandler(AddressOf backgroundCalculator_DoWork)

        AddHandler backgroundCalculator.ProgressChanged, New ProgressChangedEventHandler(AddressOf backgroundCalculator_ProgressChanged)

        AddHandler backgroundCalculator.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf backgroundCalculator_RunWorkerCompleted)



        updateStatus(String.Empty)



    End Sub



#Region "Synchronous calculation"



    Private Function getNextPrimeSync(ByVal start As Integer) As Integer



        Dim percentComplete As Integer = 0



        start += 1

        While isPrime(start) = False



            start += 1



            percentComplete += 1



            updateProgress(percentComplete Mod 100)

        End While

        Return start

    End Function



    Private Sub nextPrimeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NextPrime.Click

        enableCalcButtons(False)

        updateStatus("Calculating...")



        Dim start As Integer

        Integer.TryParse(TextPrime.Text, start)



        If start = 0 Then

            reportError("The Prime number must be a valid integer")

        Else

            Try

                Dim prime As Integer = getNextPrimeSync(start)

                reportPrime(prime)

            Catch err As ApplicationException

                reportError(err)

            End Try

            CalcProgress.Value = 0

        End If





        enableCalcButtons(True)



    End Sub

#End Region



#Region "Asynchronous calculation"



    Private Function getNextPrimeAsync(ByVal start As Integer, ByVal worker As BackgroundWorker, ByVal e As DoWorkEventArgs) As Integer



        Dim percentComplete As Integer = 0



        start += 1



        While isPrime(start) = False



            If worker.CancellationPending = True Then

                e.Cancel = True

                Exit While

            Else



                start += 1



                percentComplete += 1



                worker.ReportProgress(percentComplete Mod 100)

            End If

        End While



        Return start

    End Function



    Sub backgroundCalculator_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)



        If e.Cancelled Then

            updateStatus("Cancelled.")

        ElseIf e.Error IsNot Nothing Then

            reportError(e.Error)

        Else

            reportPrime(CInt(e.Result))

        End If



        calcProgress.Value = 0

        enableCalcButtons(True)

    End Sub



    Sub backgroundCalculator_ProgressChanged(ByVal sender As Object, ByVal e As ProgressChangedEventArgs)

        updateProgress(e.ProgressPercentage)

    End Sub



    Sub backgroundCalculator_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)

        Dim start As Integer = CInt(e.Argument)

        e.Result = getNextPrimeAsync(start, CType(sender, BackgroundWorker), e)

    End Sub



    Private Sub nextPrimeAsyncButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NextPrime.Click

        enableCalcButtons(False)

        updateStatus("Calculating...")



        Dim start As Integer

        Integer.TryParse(TextPrime.Text, start)



        If start = 0 Then

            reportError("The Prime Number must be a valid integer")

        Else

            backgroundCalculator.RunWorkerAsync(start)

        End If

    End Sub



    Private Sub cancelPrimeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NextPrime.Click

        If backgroundCalculator.IsBusy Then

            updateStatus("Cancelling...")

            backgroundCalculator.CancelAsync()

        End If

    End Sub

#End Region



#Region "User Feedback"

    Private Sub updateStatus(ByVal status As String)

        CalcStatus.Text = status

    End Sub



    Private Sub updateProgress(ByVal percentComplete As Integer)

        CalcProgress.Value = percentComplete

    End Sub



    Private Sub reportPrime(ByVal prime As Integer)

        TextPrime.Text = prime.ToString()

        updateStatus("Done!")

    End Sub



    Private Sub reportError(ByVal e As Exception)

        updateStatus("Error!")

        MessageBox.Show("The following error occurred: " + ControlChars.CrLf + e.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End Sub



    Private Sub reportError(ByVal message As String)

        updateStatus("Error!")

        MessageBox.Show("The following error occurred: " + ControlChars.CrLf + message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

    End Sub



    Private Sub enableCalcButtons(ByVal bEnable As Boolean)

        NextPrime.Enabled = True

    End Sub



#End Region



    Private Function isPrime(ByVal candidate As Integer) As Boolean



        Dim retVal As Boolean = True



        For i As Integer = candidate / 2 + 1 To 2 Step -1



            If candidate Mod i = 0 Then

                retVal = False

                Exit For

            End If

        Next



        Return retVal

    End Function

End Class

This should work... The download is to the project files which I saved. So they are virus free, thought it would be easier than having you troubleshoot with my weirdly named tools for hours...

Now to see if it can be shortened... D:

EDIT: Nvm Python will always be shorter than my vb script...

Eternal: All you have to include is a function that meets the requirements set up by Alex.

Alex: Python is basically cheating, since the syntax does not require any parenthesis or semicolons, plus, it's a language designed to be short and simple, perfect for stuff like this.

He did say any language man.

Riddle wrote:

Eternal: All you have to include is a function that meets the requirements set up by Alex.

Alex: Python is basically cheating, since the syntax does not require any parenthesis or semicolons, plus, it's a language designed to be short and simple, perfect for stuff like this.

Yeah, I was editing the code last night, out of boredom...

Well Python isn't really cheating, just an excellent choice... "it's a language designed to be short and simple, perfect for stuff like this." and thats why its unbeatable and a good language for him to choose.

I wouldn't be able to compete with python anyway...

Eternal Darkness wrote:

Yeah, I was editing the code last night, out of boredom...

Well Python isn't really cheating, just an excellent choice... "it's a language designed to be short and simple, perfect for stuff like this." and thats why its unbeatable and a good language for him to choose.

I wouldn't be able to compete with python anyway...

You can if you do certain things. You might not come at all close to winning but at least you would learn how to optimize your code.

Alrighty, since i have to learn some more complicated C and java than what i already know for the robotics team, im going to pawn you guys at this. Give me a few days as im very busy ATM.

It only takes you 5-10 minutes to come up with something that meets the requirements. >_>

ATM, i dont have 2mins for something that isnt necessary.

Sk8er took too long. Riddle wins, giving 50k LG now.

I'll buy that "Riddle The Slug Rider" rank for 50k LG. XD

If I'm not mistaken, Riddle's doesn't work. His inner loop goes from lower to upper. That will only work if lower is <= 2, otherwise it won't check to see if the number is divisible by numbers < lower.
e.g. prime numbers between 10 and 20. It will erroneously believe 12 is prime because it's not divisible by 10 or 11.



My submission even though this ended, 'cause I didn't read it until just now:

<?php



function find_primes($lower = 2, $upper = 100)

{

	$primes = Array();

	if ($lower < 2 && $upper < 2)

		return $primes;

	$temp = $upper;

	$upper = max(2, $lower, $upper); // "cache"d to prevent recalculating with each loop

	$lower = min(max(2, $lower), max(2, $temp)); // making it longer, but faster

	for ($x = $lower; $x <= $upper; ++$x)

	{

		$prime = true;

		for ($y = 2; $y < $x; ++$y)

		{

			if ($x % $y == 0)

				$prime = false;

		}

		if ($prime)

			array_push($primes, $x);

	}

	return $primes;

}



echo '<pre>';

print_r(find_primes());

print_r(find_primes(1, 30));

print_r(find_primes(30, 10));

echo '</pre>';



?>

I went for speed and functionality over character count. Note default values, the fact that the numbers can be in any order, returns an empty array instead of null, only loops from 2 to $x (instead of all the way till $upper and ignoring values where $upper > $x; compared to checking if "i > x" in Riddle's), and it supports lower values > 2 (unlike Riddle's, if I'm not mistaken).

Do I win 50k?
Since all the previous submissions do not work when lower > 2, they should be disqualified.

Revised to meet the technical requirements in the first post:

<?php



function Primes($lower = 2, $upper = 100)

{

	if ($lower < 2 && $upper < 2)

		return null;

	$primes = Array();

	$temp = $upper;

	$upper = max(2, $lower, $upper); // "cache"d to prevent recalculating with each loop

	$lower = min(max(2, $lower), max(2, $temp)); // making it longer, but faster

	for ($x = $lower; $x <= $upper; ++$x)

	{

		$prime = true;

		for ($y = 2; $y < $x; ++$y)

		{

			if ($x % $y == 0)

				$prime = false;

		}

		if ($prime)

			array_push($primes, $x);

	}

	return $primes;

}



echo '<pre>';

print_r(find_primes());

print_r(find_primes(1, 30));

print_r(find_primes(30, 10));

echo '</pre>';



?>

Shortened for character count and awesome shit removed:

<?php

function Primes($l,$u){$l=max(2,$l);if($u>$l)return null;$p=Array();for($x=$l;$x<=$u;++$x){$q=1;for($y=2;$y<$x;++$y){if($x%$y==0)$q=0;}if($q)$p[]=$x;}return $p;}

?>

Characters: 161

You sir, are completely right.

Fixed:

def Primes(l,u,p):

    if l<2:

        l=2

    if u<2:

        return

    u+=1

    for i in range(l,u):

        f=True

        for x in range(2,u):

            if i%x==0 and i!=x and i>x:

                f=False

        if f and i>=l:

            p.append(i)

    return p

Added about 7 characters: 140 total

Intriguing. The chief has potential. I should throw you some LGG for pointing that out and producing a decent function.

This should decrease the length of yours by a bit, Riddle (and increase loading speeds):

Change:

for x in range(2,u):

            if i%x==0 and i!=x and i>x:

To:

for x in range(2,i-1):

            if i%x==0:

Looping simply to i - 1, x will never be equal to i, nor will i exceed x, so we can remove both checks.

I can has the full 50k?
I am the first to actually fulfill the requirements in the original post. :flirt: