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|
d = ["\n", *File.readlines("day18").map { |x| " " + x }, "\n"]
=begin
An open acre will become filled with trees if three or more adjacent acres contained trees. Otherwise, nothing happens.
An acre filled with trees will become a lumberyard if three or more adjacent acres were lumberyards. Otherwise, nothing happens.
An acre containing a lumberyard will remain a lumberyard if it was adjacent to at least one other lumberyard and at least one acre containing trees. Otherwise, it becomes open.
=end
xd = <<EOF.lines.to_a
.#.#...|#.
.....#|##|
.|..|...#.
..|#.....#
#.#|||#|#|
...#.||...
.|....|...
||...#|.#|
|.||||..|.
...#.|..|.
EOF
require 'pp'
seen = []
p1 = 0
i = 0
d2 = nil
1000.times { |i|
pp d
d2 = d.map(&:clone)
d.each_index { |i|
d[i].chars.each_index { |j|
case d[i][j]
when '.'
if [d[i-1][j-1], d[i-1][j], d[i-1][j+1],
d[i ][j-1], d[i ][j+1],
d[i+1][j-1], d[i+1][j], d[i+1][j+1]].count('|') >= 3
d2[i][j] = '|'
end
when '|'
if [d[i-1][j-1], d[i-1][j], d[i-1][j+1],
d[i ][j-1], d[i ][j+1],
d[i+1][j-1], d[i+1][j], d[i+1][j+1]].count('#') >= 3
d2[i][j] = '#'
end
when '#'
s = [d[i-1][j-1], d[i-1][j], d[i-1][j+1], :X,
d[i ][j-1], d[i ][j+1], :Y,
d[i+1][j-1], d[i+1][j], d[i+1][j+1]]
if s.include?('#') && s.include?('|')
# keep
else
d2[i][j] = '.'
end
end
}
}
if seen.include? d2
p [:cycle, i, seen.size - seen.index(d2)]
break
else
seen << d2
end
if i == 10
r = d.join
p1 = r.count('#') * r.count('|') # 535522
end
d = d2
r = d.join
}
p p1
n = (1000000000-i)%(seen.size - seen.index(d2))
p seen.map { |s|
r = s.join
p2 = r.count('#') * r.count('|')
}.index(210160)
#p p2
# 210160
|
