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Solve 2022/16
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‎lib/2022/day_16.ex‎

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defmodule AdventOfCode.Y2022.Day16 do
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@moduledoc """
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--- Day 16: Proboscidea Volcanium ---
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Problem Link: https://adventofcode.com/2022/day/16
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Difficulty: hard
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Tags: graph floyd-warshall johnsons-algorithm dfs optimization
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"""
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import Bitwise
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alias AdventOfCode.Helpers.{InputReader, Transformers}
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alias Yog.Pathfinding.FloydWarshall
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def input, do: InputReader.read_from_file(2022, 16)
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def run(input \\ input()) do
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valves = parse(input)
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dist_map = build_dist_map(valves)
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parts_map = explore(valves, dist_map, 30)
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p1 = parts_map |> Map.values() |> Enum.max()
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p2_map = explore(valves, dist_map, 26)
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p2 =
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for {m1, f1} <- p2_map, {m2, f2} <- p2_map, band(m1, m2) == 0, reduce: 0 do
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acc -> max(acc, f1 + f2)
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end
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{p1, p2}
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end
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defp explore(valves, dist_map, time) do
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# Only care about valves with flow > 0
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relevant =
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valves |> Enum.filter(fn {_, f, _} -> f > 0 end) |> Enum.map(fn {id, f, _} -> {id, f} end)
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indices = relevant |> Enum.with_index() |> Map.new(fn {{id, _}, i} -> {id, i} end)
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memo = dfs("AA", time, 0, 0, relevant, dist_map, indices, %{})
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memo
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end
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defp dfs(curr, time, mask, flow, relevant, dist_map, indices, acc) do
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acc = Map.update(acc, mask, flow, &max(&1, flow))
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Enum.reduce(relevant, acc, fn {next, f}, acc ->
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idx = indices[next]
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dist = dist_map[{curr, next}]
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rem_time = time - dist - 1
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if band(mask, bsl(1, idx)) == 0 and rem_time > 0 do
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dfs(
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next,
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rem_time,
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bor(mask, bsl(1, idx)),
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flow + rem_time * f,
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relevant,
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dist_map,
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indices,
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acc
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)
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else
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acc
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end
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end)
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end
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defp build_dist_map(valves) do
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graph = Yog.directed()
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graph =
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Enum.reduce(valves, graph, fn {id, _, neighbors}, g ->
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Enum.reduce(neighbors, g, fn n, g_acc ->
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Yog.add_edge_ensure(g_acc, id, n, 1)
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end)
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end)
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# Use Floyd-Warshall to get all-pairs shortest paths
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{:ok, res} = FloydWarshall.floyd_warshall(graph)
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# relevant = AA + all with flow > 0
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ids = [
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"AA" | valves |> Enum.filter(fn {_, f, _} -> f > 0 end) |> Enum.map(fn {id, _, _} -> id end)
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]
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for u <- ids, v <- ids, into: %{} do
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case Map.fetch(res, {u, v}) do
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{:ok, d} -> {{u, v}, d}
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# unreachable
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:error -> {{u, v}, 1000}
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end
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end
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end
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def parse(data \\ input()) do
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data
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|> Transformers.lines()
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|> Enum.map(fn line ->
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[_, id, flow, tunnels] =
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Regex.run(~r/Valve ([A-Z]{2}) has flow rate=(\d+); tunnels? leads? to valves? (.*)/, line)
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{id, String.to_integer(flow), String.split(tunnels, ", ")}
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end)
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end
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end

‎priv/input_files/2022_16.txt‎

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Valve DB has flow rate=0; tunnels lead to valves AC, UN
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Valve LC has flow rate=6; tunnels lead to valves UV, CM, RD, IM, YQ
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Valve SU has flow rate=0; tunnels lead to valves OH, BX
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Valve JS has flow rate=0; tunnels lead to valves GR, RW
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Valve BX has flow rate=18; tunnels lead to valves PA, SU
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Valve WI has flow rate=0; tunnels lead to valves GR, JI
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Valve YQ has flow rate=0; tunnels lead to valves LC, SB
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Valve HX has flow rate=10; tunnels lead to valves VR, GZ, ID
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Valve RI has flow rate=0; tunnels lead to valves HF, UV
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Valve JQ has flow rate=0; tunnels lead to valves AA, IF
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Valve RK has flow rate=0; tunnels lead to valves AA, CM
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Valve AC has flow rate=0; tunnels lead to valves DB, HF
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Valve JI has flow rate=12; tunnels lead to valves WI, YH, ND, ID
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Valve DF has flow rate=0; tunnels lead to valves JW, AA
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Valve PA has flow rate=0; tunnels lead to valves BX, RB
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Valve OU has flow rate=0; tunnels lead to valves OH, XM
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Valve YO has flow rate=0; tunnels lead to valves OK, HF
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Valve YY has flow rate=0; tunnels lead to valves UN, MC
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Valve OJ has flow rate=0; tunnels lead to valves SC, GR
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Valve VR has flow rate=0; tunnels lead to valves IR, HX
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Valve EY has flow rate=0; tunnels lead to valves HR, OK
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Valve LE has flow rate=0; tunnels lead to valves GV, GZ
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Valve HF has flow rate=14; tunnels lead to valves DS, YO, AC, RI, WP
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Valve OM has flow rate=0; tunnels lead to valves DS, GV
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Valve JW has flow rate=0; tunnels lead to valves UN, DF
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Valve OK has flow rate=9; tunnels lead to valves IF, EY, OV, YO, WM
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Valve RB has flow rate=0; tunnels lead to valves PA, XM
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Valve HR has flow rate=0; tunnels lead to valves EY, CQ
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Valve YM has flow rate=0; tunnels lead to valves GB, NB
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Valve UN has flow rate=5; tunnels lead to valves RD, DB, JW, YY, WC
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Valve SO has flow rate=0; tunnels lead to valves AA, RH
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Valve RW has flow rate=0; tunnels lead to valves JS, GV
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Valve IF has flow rate=0; tunnels lead to valves OK, JQ
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Valve WP has flow rate=0; tunnels lead to valves HF, CQ
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Valve YK has flow rate=0; tunnels lead to valves MO, GV
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Valve MQ has flow rate=0; tunnels lead to valves AA, HI
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Valve RH has flow rate=0; tunnels lead to valves SO, GB
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Valve GB has flow rate=7; tunnels lead to valves YM, RH, PU
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Valve XM has flow rate=16; tunnels lead to valves OU, ND, NB, RB
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Valve RD has flow rate=0; tunnels lead to valves UN, LC
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Valve HI has flow rate=0; tunnels lead to valves MQ, GR
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Valve OH has flow rate=19; tunnels lead to valves OU, SU
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Valve DS has flow rate=0; tunnels lead to valves OM, HF
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Valve GV has flow rate=24; tunnels lead to valves RW, MC, YK, OM, LE
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Valve AA has flow rate=0; tunnels lead to valves SO, DF, RK, MQ, JQ
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Valve CQ has flow rate=17; tunnels lead to valves SB, MO, WP, SC, HR
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Valve UV has flow rate=0; tunnels lead to valves LC, RI
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Valve OV has flow rate=0; tunnels lead to valves OK, WC
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Valve CM has flow rate=0; tunnels lead to valves RK, LC
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Valve YH has flow rate=0; tunnels lead to valves NW, JI
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Valve GZ has flow rate=0; tunnels lead to valves LE, HX
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Valve WC has flow rate=0; tunnels lead to valves UN, OV
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Valve ID has flow rate=0; tunnels lead to valves JI, HX
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Valve SC has flow rate=0; tunnels lead to valves OJ, CQ
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Valve GR has flow rate=11; tunnels lead to valves OJ, WI, HI, PU, JS
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Valve IM has flow rate=0; tunnels lead to valves LC, WM
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Valve NB has flow rate=0; tunnels lead to valves YM, XM
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Valve TS has flow rate=20; tunnel leads to valve NW
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Valve SB has flow rate=0; tunnels lead to valves CQ, YQ
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Valve MC has flow rate=0; tunnels lead to valves GV, YY
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Valve ND has flow rate=0; tunnels lead to valves JI, XM
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Valve MO has flow rate=0; tunnels lead to valves CQ, YK
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Valve PU has flow rate=0; tunnels lead to valves GB, GR
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Valve IR has flow rate=13; tunnel leads to valve VR
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Valve NW has flow rate=0; tunnels lead to valves YH, TS
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Valve WM has flow rate=0; tunnels lead to valves IM, OK

‎test/2022/day_16_test.exs‎

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defmodule AdventOfCode.Y2022.Day16Test do
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@moduledoc false
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use ExUnit.Case, async: true
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@moduletag :y2216
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alias AdventOfCode.Y2022.Day16, as: Solution
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test "Year 2022, Day 16 run/1" do
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assert Solution.run() == {1673, 2343}
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end
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end

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