Advent of Code: Day 2 (Part 2)

$lines = [IO.File]::ReadAllText("D:\scripts\Sequences.txt") -split "[\r\n]" | where {$_}

$grid = New-Object 'object[,]'5,5
$grid[0,2] = 1
$grid[1,1] = 2
$grid[1,2] = 3
$grid[1,3] = 4
$grid[2,0] = 5
$grid[2,1] = 6
$grid[2,2] = 7
$grid[2,3] = 8
$grid[2,4] = 9
$grid[3,1] = 'A'
$grid[3,2] = 'B'
$grid[3,3] = 'C'
$grid[4,2] = 'D'

$x = 0
$y = 2

function CodeDigit($sequencetocheck){

    for($i=0; $i -lt $sequencetocheck.length; $i++){
        if($sequencetocheck[$i] -eq 'U'){
            if ($y -ne 0){
                if($grid[($y-1),$x] -ne $null){
                    $y-=1
                }
            }
        }
        elseif($sequencetocheck[$i] -eq 'D'){
            if ($y -ne 4){
                if($grid[($y+1),$x] -ne $null){
                    $y += 1
                }
            }
        }
        elseif($sequencetocheck[$i] -eq 'R'){
            if ($x -ne 4){
                if($grid[$y,($x+1)] -ne $null){
                    $x += 1
                }
            }
        }
        else{
            if ($x -ne 0){
                if($grid[$y,($x-1)] -ne $null){
                    $x -= 1
                }
            }
        }
    }
    return $grid[$y,$x]
}

$one = CodeDigit($lines[0])
$two = CodeDigit($lines[1])
$three = CodeDigit($lines[2])
$four = CodeDigit($lines[3])
$five = CodeDigit($lines[4])

write-host 'Urination Authorization Code:' $one$two$three$four$five