AoC 2023 day 18, part 2 (Smalltalk)

#!/usr/local/bin/gst -q

String extend [ asRadix: rad [^Number readFrom: (ReadStream on: self) radix: rad] ]

"
| Mainline
"
area   := 0.
pos    := (0 @ 0).
trench := 0.

stdin linesDo: [ :line |
    parts := line subStrings.

    delta := (parts third atAll: (3 to: 7)) asRadix: 16.
    dir   := (parts third at: 8) digitValue.

    vert := (dir \\ 2) = 1.                         " U and D "
    (dir >= 2) ifTrue: [ delta := delta * -1 ].     " U and L "

    vert ifTrue:  [ pos y: (pos y + delta) ]
         ifFalse: [ pos x: (pos x + delta) ].

    area := area + (delta * (vert ifTrue: [pos x] ifFalse: [-1 * pos y])).
    trench := trench + delta abs.
].

part2 := (area abs + trench) / 2 + 1.
('Part 2: %1' % {part2}) displayNl.