#https://adventofcode.com/2020/day/1

$cookie_id = "53616xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
$session = New-Object Microsoft.PowerShell.Commands.WebRequestSession
$session.Cookies.Add((New-Object System.Net.Cookie("session", $cookie_id, "/", ".adventofcode.com")))
$list = Invoke-WebRequest -UseBasicParsing -Uri "https://adventofcode.com/2020/day/1/input" 
-WebSession $session `
[int[]]$list = $list.Content -split("\n") | ? {$_}

#Slow way but works
for($i=0;$i -lt $list.Count; $i++){
    for($j=1;$j -lt $list.Count; $j++){
        if($list[$i]+$list[$j] -eq 2020){
            $answer_1 = $list[$i]*$list[$j]
        }
    }
}

#More effective but require a sorted array
$list = $list | sort
$i = 0
$j = $list.Count -1
while ($i -lt $j){
    if($list[$i]+$list[$j] -eq 2020){
        $answer = $list[$i]*$list[$j]
        return $answer
    }
    elseif ($list[$i]+$list[$j] -lt 2020){
        $i++
    }
    else{
        $j--
    }
}