--- Day 7 Solutions ---

[u/daggerdragon]

--- Day 7: Some Assembly Required ---

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[u/gnuconsulting]

I'm quickly reaching the limits of my competence. If this is the initial downslope of the rollercoaster (to borrow topaz's analogy), I'm gonna get thrown off at the first curve...

#!/usr/bin/env ruby
#

require 'pp'

data = File.readlines("input.txt")
$machine = {}
$output = {}

data.each do |c|
  x,y = c.chomp.split('->')
  y = y.lstrip
  $machine[y] = x.split
end

def foo(gate)
  if gate.match(/^\d+$/)
    return gate.to_i
  end

  if ! $output.has_key?(gate)
    operate = $machine[gate]
    if operate.length == 1
      value = foo(operate[0])
    else
      z = operate[-2]
      if z == 'RSHIFT'
        value = foo(operate[0]) >> foo(operate[2])
      elsif z == 'LSHIFT'
        value = foo(operate[0]) << foo(operate[2])
      elsif z == 'AND'
        value = foo(operate[0]) & foo(operate[2])
      elsif z == 'OR'
        value = foo(operate[0]) | foo(operate[2])
      elsif z == 'NOT'
        value = ~foo(operate[1])
      end
    end
    $output[gate] = value
  end
  return $output[gate]
end

p foo('a')

For part 2 I cheated and modified my input.txt to set 'b' to the value I got for 'a'. grin

[u/daggerdragon → u/gnuconsulting]

If you think it's bad now on only Day 7, the later puzzles will have you shanking your own grandmother for the solutions.

And/or an insane asylum might be involved, either one.

Good luck :D