81 lines
2.1 KiB
Ruby
81 lines
2.1 KiB
Ruby
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#!/usr/bin/env ruby
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input = (ARGV.first.nil? ? DATA : ARGF)
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.readlines(chomp: true)
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split = input.index("")
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registers = input[...split]
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.map { _1.split(": ").last.to_i }
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.zip(%i[A B C]).map(&:reverse)
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.to_h
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program = input[split+1].split(" ").last.split(",").map(&:to_i)
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def execute(registers, program)
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stdout, ic = Array.new, 0
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combo = ->(operand) { operand < 4 ? operand : registers.values[operand - 4] }
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while ic < program.size
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opcode, operand = program[ic], program[ic + 1]
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ic += 2
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case opcode
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when 0 then registers[:A] = registers[:A] / 2 ** combo.(operand)
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when 1 then registers[:B] = registers[:B] ^ operand
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when 2 then registers[:B] = combo.(operand) % 8
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when 3 then registers[:A] == 0 || ic = operand
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when 4 then registers[:B] = registers[:B] ^ registers[:C]
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when 5 then stdout << combo.(operand) % 8
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when 6 then registers[:B] = registers[:A] / 2 ** combo.(operand)
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when 7 then registers[:C] = registers[:A] / 2 ** combo.(operand)
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end
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end
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stdout
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end
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part_1 = execute(registers.dup, program).join(",")
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p part_1
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def reverse_engineer(program, slot, candidate)
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return candidate if slot < 0
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candidate <<= 3 unless slot == program.size - 1
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(0..7)
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.map { [candidate + _1, execute({A: candidate + _1, B: 0, C: 0}, program)] }
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.select { _1.last == program[slot..] }
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.flat_map { reverse_engineer(program, slot - 1, _1.first) }
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end
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p reverse_engineer(program, program.size - 1, 0).sort.first
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# part_2 = 0
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# (program.size - 1).downto(0) do |slot|
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# candidates = []
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# (0..8).each do |i|
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# candidate = part_2 + i
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# _, _, output = execute({A: candidate, B: 0, C: 0}, program)
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# new_program = output.split(",").map(&:to_i)
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#
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# if new_program == program[slot..]
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# candidates << candidate
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# unless [301,2566855701950, 20534845615581, 20534845615573, 20534845615583].include?(candidate)
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# part_2 = candidate
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# end
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# end
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# end
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# p candidates
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# if slot == 0
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# p candidates.first
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# end
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# part_2 <<= 3
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# end
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__END__
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Register A: 117440
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Register B: 0
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Register C: 0
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Program: 0,3,5,4,3,0
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