blob: 7aa7f4351305427589454155b974aa9ebf23adc0 (
plain)
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input = File.readlines('input.txt').map { |l| ".#{l.chomp}.".split '' }
input.unshift(['.'] * input[0].length)
input.push(['.'] * input[0].length)
next_map = []
input.size.times do
row = []
input[0].size.times do
row.push '.'
end
next_map.push row
end
changed = true
current_count = 0
while changed
current_count = 0
changed = false
(1...input.length-1).each do |i|
(1...input[0].length-1).each do |j|
if input[i][j] != '.'
count = 0
(-1..1).each do |di|
(-1..1).each do |dj|
if !(di == 0 && dj == 0)
count += input[i+di][j+dj] == '#' ? 1 : 0
end
end
end
if count == 0 && input[i][j] == 'L'
next_map[i][j] = '#'
changed = true
elsif count >= 4 && input[i][j] == '#'
next_map[i][j] = 'L'
changed = true
else
next_map[i][j] = input[i][j]
end
current_count += next_map[i][j] == '#' ? 1 : 0
end
end
end
tmp = input
input = next_map
next_map = tmp
end
puts current_count
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