#!/usr/bin/env ruby

require "debug"

input = (ARGV.first.nil? ? DATA : ARGF)
  .readlines(chomp: true)
  .map(&:to_i)

def evolve(secret)
  a = ((secret * 64) ^ secret) % 16777216
  b = ((a / 32) ^ a) % 16777216
  c = ((b * 2048) ^ b) % 16777216
end

part_1 = input.map do |secret|
  original = secret
  2000.times { secret = evolve(secret) }

  secret
end.sum

p part_1

sequences = input.map do |secret|
  secrets = 2000.times
    .map { secret = evolve(secret) }

  prices = secrets.map { _1.digits.first }

  changes = prices
    .map.with_index { |p, i| i == 0 ? 0 : p - prices[i - 1] }

  sequences = Hash.new
  changes[1..].each_cons(4).with_index.each do |sequence, i|
    sequences[sequence] ||= prices[i + 4]
  end

  sequences
end

unique_sequences = sequences.flat_map(&:keys).uniq

part_2 = unique_sequences.map do |sequence|
  sequences.sum { _1.fetch(sequence, 0) }
end.max

p part_2

__END__
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