Day9

    # Part 1
    [string[]]$moves = $puzzleInput -split '\n' | Select -SkipLast 1
    $position = [ordered]@{}
    $position.move = ''
    $position.H = [ordered]@{}
    $position.H.x = 0
    $position.H.y = 0
    $position.T = [ordered]@{}
    $position.T.x = 0
    $position.T.y = 0

    $tHistory = [System.Collections.Generic.List[string]]::New()

    foreach ($move in $moves) {
        $direction, [int]$steps = $move -split '\s'
        $position.move = $move
        for ($step = 1; $step -le $steps; $step++) {
            # Move H
            switch ($direction) {
                'L' {$position.H.x--}
                'R' {$position.H.x++}
                'U' {$position.H.y++}
                'D' {$position.H.y--}
            }
            # Move Tail?
            $pDiffX = $position.H.x - $position.T.x
            $pDiffY = $position.H.y - $position.T.y
            if ($pDiffX -gt 1 -or $pDiffX -lt -1 -or $pDiffY -gt 1 -or $pDiffY -lt -1) {
                switch ($direction) {
                    'L' {
                        $position.T.x = $position.H.x+1
                        $position.T.y = $position.H.y
                    }
                    'R' {
                        $position.T.x = $position.H.x-1
                        $position.T.y = $position.H.y
                    }
                    'U' {
                        $position.T.x = $position.H.x
                        $position.T.y = $position.H.y-1
                    }
                    'D' {
                        $position.T.x = $position.H.x
                        $position.T.y = $position.H.y+1
                    }
                }
                $tHistoryStr = '{0},{1}' -f $position.T.x,$position.T.y
                $tHistory.Add($tHistoryStr)
            }
    }
    $tHistoryHS = [System.Collections.Generic.HashSet[string]]::New([string[]]$tHistory)
    $tHistoryHS.count