#!/usr/bin/env ruby

INPUT = __dir__ + '/input'
OUTPUT = 19690720

def part1
  File.readlines(INPUT).map { |line| execute(correct(to_opcode(line))).join(',') }
end

def part2
  File.readlines(INPUT).map do |line|
    opcodes = to_opcode(line)
    (0..99).each do |i|
      (0..99).each do |j|
        opcodes[1] = i
        opcodes[2] = j
        result = execute(opcodes.dup)
        return 100 * i + j if result[0] == OUTPUT
      end
    end
  end
  return nil
end

def to_opcode(line)
  line.chomp.split(',').map(&:to_i)
end

def correct(opcodes)
  opcodes[1] = 12
  opcodes[2] = 2
  opcodes
end

def execute(opcodes)
  i = 0
  while i < opcodes.size
    opcode = opcodes[i]

    if opcode == 1
      opcodes[opcodes[i + 3]] = opcodes[opcodes[i + 1]] + opcodes[opcodes[i + 2]]
    elsif opcode == 2
      opcodes[opcodes[i + 3]] = opcodes[opcodes[i + 1]] * opcodes[opcodes[i + 2]]
    else
      break
    end

    i += 4
  end

  opcodes
end

puts "=== Part 1 ==="
puts part1
puts "=== Part 2 ==="
puts part2