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advent-of-code/day21/day21.rb

89 lines
2.1 KiB
Ruby

#!/usr/bin/env ruby
grid = [ ['.', '#', '.'],
['.', '.', '#'],
['#', '#', '#'] ]
def string_to_grid(string)
string.chomp.split("/").map do |row|
row.split("")
end
end
def get_permutations(grid, depth = 0)
return [grid] if depth == 4
flipped = grid.map(&:reverse)
rotated = grid.transpose.map(&:reverse)
flipped_and_rotated = rotated.map(&:reverse)
[ grid, flipped, flipped_and_rotated ].concat(get_permutations(rotated, depth + 1)).uniq
end
def get_input_rules(filename)
sum = {}
File.readlines(filename).each do |line|
source, dest = line.split(" => ")
sgrid = string_to_grid(source)
dgrid = string_to_grid(dest)
get_permutations(sgrid).each do |perm|
sum[perm] = dgrid
end
end
sum
end
def break_grid_into(grid, size)
results = []
split = grid[0].size / size
split.times do |i|
grid[i * size, size].each_with_index do |row, index|
split.times do |j|
results[i] ||= []
results[i][j] ||= []
results[i][j] << row[j * size, size]
end
end
end
results
end
def recombine_grid(grid)
results = []
size = grid[0][0].size
grid.each_with_index do |row, k|
size.times do |i|
row_index = size * k + i
row.size.times do |j|
results[row_index] ||= []
results[row_index].concat(row[j][i])
end
end
end
results
end
def process_grid(grid, rules, depth = 5)
if depth == 0
grid.each { |row| puts row.join("") }
puts grid.flatten.select { |x| x == "#" }.size
return
end
new_size = grid[0].length.even? ? 2 : 3
new_grid = break_grid_into(grid, new_size)
mutated = new_grid.map do |row|
row.map do |entry|
if rules[entry].nil?
rules.each { |k, v| puts "#{k} => #{v}" }
raise "#{entry.inspect} has no match"
else
rules[entry]
end
end
end
mutated_grid = recombine_grid(mutated)
process_grid(mutated_grid, rules, depth - 1)
end
process_grid(grid, get_input_rules('sample'), 2)
process_grid(grid, get_input_rules('problem'), 5)
process_grid(grid, get_input_rules('problem'), 18)