USING: arrays io.encodings.ascii io.files kernel literals math
math.matrices math.vectors prettyprint sequences sequences.extras ;
IN: aoc.2020.03

<< CONSTANT: input
    $[ "resource:work/aoc/2020/03/input.txt" ascii file-lines ] >>

CONSTANT: width $[ input first length ]

: trees ( fall run -- n )
    input length pick /i -rot 2array <repetition>
    { 0 0 } [ v+ first2 width mod 2array ] accumulate nip
    input matrix-nths [ CHAR: # = ] count ;

1 3 trees .   ! part1
1 1 trees 1 3 trees 1 5 trees 1 7 trees 2 1 trees * * * * .   ! part2