Wednesday, April 23, 2008 3:46:13 AM UTC

If you aren't already in the know, these ten problems are from the 2008 Winter Scripting games.

For each problem, I'm going to quickly sum up the interesting (interesting TO ME) bits of each problem, then I'm going to post the full source.

Event 7: Play Ball!

Here we are asked to randomly schedule games for six teams in a round robin tournament. Apparently I used Knuth's classic list order randomization algorithm, which I remember attempting to implement, badly, and failing!, in high school. Yay for progress.

Otherwise the solution is straightforward: two nested loops, generate matches in a "combinatorial" way, then randomize the order. Boom, done.

Source

#PROBLEM #7 
$teams = @("A", "B", "C", "D", "E", "F") 


#bad random number generator 
$rnd = new-object Random 


function Create-GameObject ($game) 
{ 
    $o = new-object PSObject 
    Add-Member -inputObject $o -memberType NoteProperty -name "Game" -value $game 
    
    Add-Member -inputObject $o -memberType NoteProperty -name "RandomOrder" -value $rnd.NextDouble()    
    
    $o 
} 


function Generate-RoundRobinGames 
{ 
    for ($firstTeamIndex = 0; $firstTeamIndex -lt $teams.Count; $firstTeamIndex++) 
    { 
        for ($secondTeamIndex = $firstTeamIndex + 1; $secondTeamIndex -lt $teams.Count; $secondTeamIndex++) 
        { 
            #POSTSCRIPT-OOPS - nitpick mostly. Reading MOW's solution has enlightened me 
            #that, instead of creating objects and bolting properties onto them one at a time 
            #as I do in the function referenced below, I could achieve the same result with 
            #some well-constructed 
            #    Select-Object @{Name=""; Expression={"stuff goes here"} } 
            #statements. 
            Create-GameObject -game "$($teams[$firstTeamIndex]) vs. $($teams[$secondTeamIndex])" 
        } 
    } 
} 


function Solve-Problem7 
{ 
    $unsortedGames = Generate-RoundRobinGames 


    Write-Host ($unsortedGames | sort RandomOrder | % { $_.Game } | out-string) 
} 


Solve-Problem7 

2008 Winter Scripting Game Events: Index

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Wednesday, April 23, 2008 3:46:13 AM UTC

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"2008 Winter Scripting Games Event 8" (Peter Seale's weblog) [Trackback]
"2008 Winter Scripting Games Event 9" (Peter Seale's weblog) [Trackback]
"2008 Winter Scripting Games Event 10" (Peter Seale's weblog) [Trackback]
"2008 Winter Scripting Games: Recap" (Peter Seale's weblog) [Trackback]

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Event 7: Play Ball!

Source

2008 Winter Scripting Game Events: Index