Reddit Daily Programmer #236 Solution

pick-tetromino.ps1

#Reddit Daily Programmer 236.
#https://www.reddit.com/r/dailyprogrammer/comments/3ofsyb/20151012_challenge_236_easy_random_bag_system/

#Initialize the array with all pieces.
$pieces = New-Object System.Collections.ArrayList
$counter = 0
$result = ""

#Pick the pieces.
while($counter -lt 50) {
	#Fill the initial "bucket" with pieces.
	$pieces.Add("O") | Out-Null
	$pieces.Add("I") | Out-Null
	$pieces.Add("S") | Out-Null
	$pieces.Add("Z") | Out-Null
	$pieces.Add("L") | Out-Null
	$pieces.Add("J") | Out-Null
	$pieces.Add("T") | Out-Null
	
	#Loop through the letters until none are left!
	while($pieces.Count -gt 0) {
		#Pick a random number for the next piece.
		if($pieces.Count -gt 1) {
			$randomNum = Get-Random -Minimum 0 -Maximum ($pieces.Count - 1)
		} else {
            #Min and Max can't be the same value (0) so this is needed to finish off the bucket.
			$randomNum = 0
		}
		
		#Append to the results.
		$result += $pieces[$randomNum]
		
		#Remove that item from the array.
		$pieces.RemoveAt($randomNum)
		
		#Increment the counter.
		$counter++

    #Break out of this IF we surpass the specified limit of pieces to generate.
    if($counter -ge 50) {
        break
    }
	}
}

#Output the results.
Write-Host $result

#Verify the output! Note the prompt specifies we always produce 50 pieces.
#This assumes the number could be variable to be a bit more resilient.
$resultArray = $result.ToCharArray()
$overCount = 0
$checkArray = New-Object System.Collections.ArrayList
$broken = $false

foreach($item in $resultArray) {
    #Add to the check array and increment the counter.
    $checkArray.Add($item) | Out-Null
    $overCount++

    <#Intentionally break stuff for testing. To use this, comment out the .Add on line 58.
    if($overCount -lt 3) {
        $checkArray.Add("J") | Out-Null
    } else {
        $checkArray.Add($item) | Out-Null
    }#>

    #Check each grouping of 7 characters OR if we're at the end check whatever is left.
    if((($overCount % 7) -eq 0) -or ($overCount -eq $resultArray.Count)) {
        #Put all the stuff into another list we can modify while enumerating through the original.
        $fubarArray = New-Object System.Collections.ArrayList
        foreach($item in $checkArray) {
            $fubarArray.Add($item) | Out-Null
        }

        #Now check the "main" array.
        foreach($item in $checkArray) {
            #Check just one level deep. If it's found twice, script's broken. Don't care about more brokenness beyond that.
            $index = $fubarArray.IndexOf($item)
            $fubarArray.RemoveAt($index)

            #Should always be -1 if we aren't borked. Kill it right away if it's not.
            $index = $fubarArray.IndexOf($item)
            if($index -ne -1) {
                $broken = $true
                break
            }
        }

        #Clear the arraylist for the next run so we don't build on top of it.
        $checkArray.Clear()
    }

    #Break again if we're busted since this loop will no longer matter.
    if($broken) {
        break
    }
}

#Print if everything is valid or not.
if($broken) {
    Write-Host "Output is not valid!"
} else {
    Write-Host "Output is valid!"
}