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  • As Ethic falls, she remembers.

  • She remembers the world before they unearthed the crystal.

  • She remembers the glee she felt when she built her first robot.

  • But mostly she remembers the friends she's made

  • these last few days:

  • courageous Adila and her resistance movement.

  • Octavia's sacrifice to keep the guards distracted.

  • Lemma and her idealistic drive to cure everyone.

  • And Hedge.

  • Her creation, her responsibility, her failureher betrayer.

  • Hedge, who convinced her to collect the three nodes

  • that she never actually needed.

  • For Ethic remembers how to operate the World Machine.

  • If only she could get a second chance at it.

  • Adila has been in radio contact with Octavia,

  • whom the robots captured and imprisoned in the same jail that held Ethic.

  • Ethic explains that Hedge has manipulated them all,

  • and will now try to break down the Bradbarrier

  • and cover the entire world in a giant maze,

  • unless they can stop him.

  • But she has a plan:

  • Ethic herself will go to the crystal at the center of the maze

  • and use its powers to stop Hedge.

  • Meanwhile, Adila and Lemma will do whatever they can to slow Hedge down.

  • As Ethic weaves her way towards the innermost maze,

  • her radio picks up a transmission.

  • Octavia has freed hundreds of members of the resistance from stasis.

  • Together, they've staged a jailbreak and overwhelmed the guards.

  • The resistance has access to the World Machine,

  • but they don't know how to use it; they'll need Ethic for that.

  • All they have at their disposal are nearly limitless spools of wire.

  • The strands are durable, but prisoners can break them deliberately

  • if they need to.

  • Ethic reaches the entrance to the inner most mazeand it's sealed from within.

  • She remembers a few things from when she flew over the maze days earlier.

  • It centers on the crystal.

  • There are many dead ends, but no paths that loop back on themselves.

  • Ethic has one opportunity to radio the members of the resistance

  • a simple set of instructions

  • before they plunge into the labyrinth in search of the exit.

  • What directions can she give them so they can quickly navigate the maze,

  • open the door, and guide Ethic straight back to the crystal?

  • Pause now to figure it out for yourself.

  • Hint in 3

  • Hint in 2

  • Hint in 1

  • Here's a hint:

  • One of the challenges here is to find a way to indicate where dead ends are,

  • so that the resistance members don't keep going down them.

  • Try simplifying the maze to something like this.

  • Let's say you've just hit this dead end, then came back to this intersection.

  • What could you do to show the next person who gets here

  • that they don't need to explore that path?

  • Pause now to figure it out yourself.

  • Solution in 3

  • Solution in 2

  • Solution in 1

  • Most programming puzzles involve giving instructions to a single actor

  • so that they can accomplish a goal.

  • Instead, here we have a swarm of individuals,

  • each of whom can follow basic instructions.

  • That's unusual in programming, but not unheard of;

  • researchers are currently experimenting with swarms of small robots

  • to do things like conduct search and rescue missions.

  • The prisoners aren't robots, but for Ethic's purposes they'll act like them.

  • And by working together they can achieve their goal much more efficiently.

  • Because you have a lot of prisoners, you'll want them to cover a lot of ground.

  • This matches up well to a maze-mapping technique called a depth-first search.

  • It's called that because it involves going as deeply down a path as possible

  • before going back.

  • In other words, if you had a maze like this,

  • you'd want to explore all the way down one of these branches

  • before returning to this intersection and trying another.

  • Everyone needs a clear set of instructions for what they should do.

  • Likefirst, tie down the loose end of your wire by the crystal,

  • so it leads back there.

  • If you find the door, open it and hand your spool to Ethic.

  • If you're in a passageway, keep going until you hit a dead end

  • or an intersection.

  • But what happens at either of those places?

  • If someone encounters a dead end,

  • they should backtrack to the last intersection.

  • But they also need to mark it, so no one wastes time and goes back there.

  • The best tool for that is the wire

  • one option is to break both sections that lead down the dead end path,

  • and tie the spool to the wire that leads back to the crystal.

  • The broken wires tell everyone else who gets to this intersection

  • Don't go this way.”

  • They'll also guarantee the final path will lead straight to the crystal,

  • rather than visiting dead ends.

  • Ok, so let's say someone's at an intersection.

  • Now which way should they go?

  • The first priority is to have everyone cover fresh ground

  • to minimize doubling up.

  • So if there's no wire down a direction, go that way.

  • If there are multiple choices, choose one at random.

  • What if they're in a sub-section like this, with 3 marked dead ends?

  • The only thing to do is to go back where they came from.

  • We now know that this whole section is one big dead end,

  • so they should break and retie the wire when they get to the next intersection.

  • But let's say they get there, and find two options where someone's exploring,

  • but no one's hit a dead end yet.

  • They may as well choose at random and go help explore that path further,

  • in case it's the right direction for the exit.

  • This isn't the only way to solve this challenge, but in any correct method,

  • someone will eventually find the way out.

  • The moment of truth will be when Ethic takes their wire and follows it back,

  • inward towards her goal.

  • The great thing about this method is that Ethic's path is straight and true.

  • The maze doesn't have loops, so there's only one path from door to crystal.

  • And because everyone has been breaking and retying their wires,

  • Ethic won't go down any dead-end paths.

  • Face to face with her creation, Ethic has a choice:

  • she can destroy Hedge, or set things right.

  • All of this destruction was her fault, not Hedge's;

  • it was her oversight that instructed him to build an infinitely large maze.

  • His decisions were misguided, but everything he did,

  • he did to follow his programming.

  • Ethic accesses his core and fixes her error with a single number:

  • the size the maze was supposed to reach.

  • Ethic has prevented catastrophe

  • and regained possession of the World Machine.

  • Her work with Adila, Octavia, and Lemma has already started to help people

  • and heal the world's turmoil, but there's much work to be done.

  • With the forgetting food out of their systems,

  • the people will become themselves again.

  • They'll regain their will to create and progress.

  • They'll be free to break down the walls they've built between each other.

  • And they may come to approach their future with a little less greed

  • and a little more... Ethic

As Ethic falls, she remembers.

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B1 ethic maze intersection hedge dead wire

The World Machine | Think Like A Coder, Ep 10

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    林宜悉 posted on 2020/11/30
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