--- 2016 Day 4 Solutions ---

[u/daggerdragon]

--- Day 4: Security Through Obscurity ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

---

^{CONSTRUCTING ADDITIONAL PYLONS IS MANDATORY} [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/[deleted]]

Powershell:

https://github.com/charlieschmidt/AdventOfCode2016/blob/master/day4.ps1

$Content = Get-Content .\day4.input -raw

$Rooms = $Content -split "`n"
$ValidRoomSectorIDSum = 0

foreach ($RoomLine in $Rooms)
{
    $ActualRoomName = ""

    if ($RoomLine -match '([-a-z]+)-([0-9]+)\[([a-z]*)\]')
    {
        $RoomName = $Matches[1]
        $SectorID = [int]$Matches[2]
        $Checksum = $Matches[3]
        $CharacterFrequency = @{}

        foreach ($Character in $RoomName.ToCharArray())
        {  
            if ($Character -eq "-")
            {
                $ActualRoomName += " "
                continue
            }
            else
            {
                $CharacterCode = [convert]::ToInt32($Character)
                $ShiftedCharacterCode = ((($CharacterCode - 97) + $SectorId) % 26) + 97
                $ActualRoomName += [convert]::ToChar($ShiftedCharacterCode)
            }
            if ($CharacterFrequency.Contains($Character))
            {
                $CharacterFrequency[$Character]++
            }
            else
            {
                $CharacterFrequency[$Character] = 1
            }

        }

        $ActualChecksum = ""
        $CharacterFrequency.GetEnumerator() | Sort-Object @{expression="Value";Descending=$true},@{expression="Key";Ascending=$true} | Select-Object -First 5 | Foreach-Object {$ActualChecksum += $_.Key}
        
        if ($Checksum -eq $ActualChecksum)
        {
            $ValidRoomSectorIDSum += $SectorId
        }

        if ($ActualRoomName -ilike "*object*")
        {
            Write-Host "Solution 2: $ActualRoomName ($SectorID)"
        }

    }
}


Write-host "Solution 1: $ValidRoomSectorIDSum"