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104 lines
2.2 KiB
104 lines
2.2 KiB
require "set"
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Valve = Data.define(:name, :flow_rate, :tunnels)
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valves = ARGF.read.scan(/Valve (.+) has flow rate=(\d+); tunnels? leads? to valves? ((?~\n))/)
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.map {|name, flow_rate, tunnels|
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Valve.new(name, flow_rate.to_i, tunnels.split(", "))
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}
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Network = Data.define(:valves) do
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def initialize(*)
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@connections = Hash.new {|h,start|
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current = [[start]]
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result = { start => %w[ AA ] }
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until current.empty?
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path = current.shift
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links = valves.fetch(path.last).tunnels
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.reject { result.has_key?(_1) }
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.map { path + [_1] }
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result.merge!(links.to_h { [_1.last, _1] })
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current.concat(links)
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end
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h[start] = result
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}
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super
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end
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def connections(start) = @connections[start]
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end
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Move = Data.define(:reward, :target, :path) do
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def cost = path.length
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end
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State = Data.define(:net, :current, :max, :turn, :pressure, :opened) do
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def best_moves(best)
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best_state = self
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best[opened] = [best.fetch(opened, pressure), pressure].max
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moves.each do |move|
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next_state = applied(move)
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next_state = next_state.best_moves(best);
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if next_state.pressure > best_state.pressure
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best_state = next_state
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end
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end
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best_state
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end
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def applied(move)
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self.class.new(
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net,
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move.target,
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max,
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turn + move.cost,
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pressure + move.reward,
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Set[*opened, move.target],
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)
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end
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def moves
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return enum_for(__method__) unless block_given?
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net
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.connections(current)
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.reject { opened.include?(_1) }
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.each do |name, path|
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flow = net.valves.fetch(name).flow_rate
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reward = flow * (turns_left - path.length)
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if reward.positive?
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yield Move.new(reward, name, path)
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end
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end
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end
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def turns_left = max - turn
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end
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network = Network.new(valves.to_h { [_1.name, _1] })
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# part 1
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# state = State.new(network, "AA", 30, 0, 0, [])
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# best_state = state.best_moves({})
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# pp best_state
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# part 2
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state = State.new(network, "AA", 26, 0, 0, [])
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best = {}
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state.best_moves(best)
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pp best
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.transform_keys(&:to_set)
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.to_a
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.combination(2)
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.select { _1[0].disjoint?(_2[0]) }
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.map { _1[1] + _2[1] }
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.max
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