frontpage.
newsnewestaskshowjobs

Made with ♥ by @iamnishanth

Open Source @Github

fp.

Open in hackernews

Generating Mazes with Inductive Graphs (2017)

https://jelv.is/blog/Generating-Mazes-with-Inductive-Graphs/
20•todsacerdoti•1y ago

Comments

tomfly•1y ago
where is the entrance and exit?
Jaxan•1y ago
Doesn’t matter, because all positions are reachable. So just pick any two positions at the border and remove a wall.
kazinator•1y ago
Here is a maze that was generated recursively starting at the upper left cell.

  +    +----+----+----+----+----+----+----+----+----+
  |    |                        |                   |
  |    |                        |                   |
  +    +----+----+    +----+    +----+    +----+    +
  |              |         |                   |    |
  |              |         |                   |    |
  +----+----+    +    +----+----+----+----+----+    +
  |              |    |                        |    |
  |              |    |                        |    |
  +    +----+----+    +    +----+----+----+    +    +
  |         |              |              |    |    |
  |         |              |              |    |    |
  +    +----+    +    +----+----+----+    +    +----+
  |              |    |                   |    |    |
  |              |    |                   |    |    |
  +----+----+----+    +    +----+----+----+    +    +
  |                        |                   |    |
  |                        |                   |    |
  +    +----+----+----+    +    +----+----+----+    +
  |    |    |              |    |              |    |
  |    |    |              |    |              |    |
  +    +    +    +    +----+    +    +----+    +    +
  |    |    |    |    |         |    |         |    |
  |    |    |    |    |         |    |         |    |
  +    +    +    +    +----+----+----+    +    +    +
  |    |    |    |    |                   |         |
  |    |    |    |    |                   |         |
  +    +    +----+    +    +----+----+    +----+----+
  |              |         |                        |
  |              |         |                        |
  +----+----+----+----+----+----+----+----+----+    +

It matters to start there because it will be easier if you go backwards.

The maze has 100 cells. For each cell, we can calculate which exit goes back toward the entrance, assigning the letters U, D, L, R:

  U R R D L L R D L L
  U L L D L U L L L U
  R R U D D L L L L U
  U L D L L R R D U U
  U L L U D L L L U D
  R R R U L R R R U D
  U D R R U U R R D D
  U D U U R U U D L D
  U D U U D L L L U L
  U L L U L R R U L L
Stats:

  L - 33
  U - 29
  R - 20
  D - 18
Left and Up are more frequent back-to-entrance escapes than Right or Down. This is because of the way the maze was generated.

To check the hypothesis, we should analyze it in the other direction. For each cell, determine the exit which heads in the direction of the exit:

  D R R D L L R D L L
  D R D D L U L L L U
  D L L D D L L L L U
  D L R D L R R D D U
  R R U D D L L L U D
  R R R R D R R R U D
  U D R D L U R R D D
  U D U D R U U D L D
  U D U D R R R D U L
  U L L R U R R R R D
Stats:

  D - 30
  R - 28
  L - 24
  U - 18
There is a weaker bias for the D-R axis toward the exit, compared to the L-U axis toward the entrance. I suspect if we study larger numbers of larger mazes, we will find similar findings.

So that is to say, it is easier to navigate the maze in the reverse direction: the heuristic to try left/up exits will work more often than the right/down in the proper direction.

smartmic•1y ago
From the book "Mazes for Programmers" by Jamis Buck, 2015, The Pragmatic Programmers (a must-read for any maze/programming enthusiast!):

> Aren't mazes supposed to have starting points and end points? […] honestly, […] it's entirely up to you. […] The maze […] is a perfect maze, and one of the attributes of a perfect maze is that there exists exactly one path between any two cells in it. […] You pick them, and there's guaranteed to be a path between them.

You do not need to choose an entrance or exit only on the sides, but you can also choose "Pacman-style" where the goal is to reach points inside the maze.

"Perfect" refers to the mathematical/logical properties of a maze (i.e. no loops), not the aesthetical aspect. I have not checked though if the mazes in the source here are all perfect.

kazinator•1y ago
While you can put the entrance and exit wherever you want, if you know that the maze was generated by a recursive branching process which had a starting point somewhere, it probably behooves you to put the start at that point corresponding to the root of the tree, so that the maze wanderer faces the most branching choices.

Laying out the abstract maze tree into the rectilinear grid of cells obfuscates the tree somewhat, but not entirely. A process that generates from upper left to lower right, for instance, will tend to generate cells whose parent-headed exits going left and up more often than not, making the reverse direction a bit easier.

(Again, it depends on the maze generation process.)

kazinator•1y ago
Making random mazes in a rectilinear grid is a good exercise for one big reason: mazes are not all the same. Mazes have style can be very knotty and twisty, or have long passages. You can add hacks into a given algorithm to vary the style, but there are certain things it won't necessarily do.

Show HN: Perfect Bluetooth MIDI for Windows

35•mayerwin•2h ago•4 comments

Your Website Is Not for You

https://websmith.studio/blog/your-website-is-not-for-you/
7•pumbaa•46m ago•2 comments

Show HN: WhatCable, a tiny menu bar app for inspecting USB-C cables

https://github.com/darrylmorley/whatcable
138•sleepingNomad•3h ago•44 comments

How Mark Klein told the EFF about Room 641A [book excerpt]

https://thereader.mitpress.mit.edu/the-whistleblower-who-uncovered-the-nsas-big-brother-machine/
616•the-mitr•19h ago•208 comments

Grok 4.3

https://docs.x.ai/developers/models/grok-4.3
131•simianwords•3h ago•156 comments

New copy of earliest poem in English, written 1,3k years ago, discovered in Rome

https://www.tcd.ie/news_events/articles/2026/caedmons-hymn-discovery/
84•giuliomagnifico•2d ago•52 comments

For Linux kernel vulnerabilities, there is no heads-up to distributions

https://www.openwall.com/lists/oss-security/2026/04/30/10
519•ori_b•19h ago•415 comments

OpenWarp

https://openwarp.zerx.dev
106•zero-lab•9h ago•91 comments

A beginner's guide to Sourcehut (2025)

https://btxx.org/posts/beginners-guide-sourcehut/
23•bradley_taunt•1h ago•4 comments

Softmax, can you derive the Jacobian? And should you care?

https://idlemachines.co.uk/essays/softmax
62•smaddrellmander•3d ago•6 comments

Shai-Hulud Themed Malware Found in the PyTorch Lightning AI Training Library

https://semgrep.dev/blog/2026/malicious-dependency-in-pytorch-lightning-used-for-ai-training/
405•j12y•19h ago•147 comments

The Rotary Un-Smartphone

https://skysedge.com/telecom/RUSP/index.html
35•tzury•2h ago•5 comments

Opus 4.7 knows the real Kelsey

https://www.theargumentmag.com/p/i-can-never-talk-to-an-ai-anonymously
369•ilamont•1d ago•193 comments

If I could make my own GitHub

https://matduggan.com/if-i-could-make-my-own-github/
16•matricaria•22h ago•50 comments

Maladaptive Frugality

https://herbertlui.net/maladaptive-frugality/
120•herbertl•2d ago•93 comments

After dissing Anthropic for limiting Mythos, OpenAI restricts access to Cyber

https://techcrunch.com/2026/04/30/after-dissing-anthropic-for-limiting-mythos-openai-restricts-ac...
51•gbourne1•1h ago•27 comments

Auto Polo

https://en.wikipedia.org/wiki/Auto_polo
73•canjobear•2d ago•19 comments

How an oil refinery works

https://www.construction-physics.com/p/how-an-oil-refinery-works
438•chmaynard•22h ago•136 comments

Claude Code refuses requests or charges extra if your commits mention "OpenClaw"

https://twitter.com/theo/status/2049645973350363168
1190•elmean•21h ago•658 comments

CPanel and WHM Authentication Bypass – CVE-2026-41940

https://labs.watchtowr.com/the-internet-is-falling-down-falling-down-falling-down-cpanel-whm-auth...
117•zikani_03•13h ago•48 comments

I built a Game Boy emulator in F#

https://nickkossolapov.github.io/fame-boy/building-a-game-boy-emulator-in-fsharp/
288•elvis70•18h ago•66 comments

Can I disable all data collection from my vehicle?

https://rivian.com/support/article/can-i-disable-all-data-collection-from-my-vehicle
641•Cider9986•15h ago•266 comments

Apple accidentally left Claude.md files Apple Support app

https://xcancel.com/aaronp613/status/2049986504617820551
19•andruby•46m ago•2 comments

You can beat the binary search

https://lemire.me/blog/2026/04/27/you-can-beat-the-binary-search/
327•vok•3d ago•144 comments

Roboticist-Turned-Teacher Built a Life-Size Replica of Eniac

https://spectrum.ieee.org/roboticist-turned-teacher-eniac-replica
35•oldnetguy•1d ago•8 comments

New mechanical panoramic film camera from Jeff Bridges

https://wideluxx.com
157•armadsen•2d ago•74 comments

Canonical/Ubuntu have been under DDoS for more than 15h

https://status.canonical.com/#/incident/KNms6QK9ewuzz-7xUsPsNylV20jEt5kyKsd8A-3ptQEHpOd8VQ40ZQs-K...
72•jtlebigot•4h ago•23 comments

Reverse Engineering SimTower

https://phulin.me/blog/simtower
211•patrickhulin•2d ago•47 comments

Our agent found a bug with WireGuard in Google Kubernetes Engine

https://lovable.dev/blog/hunting-networking-bugs-in-kubernetes
20•vikeri•3h ago•0 comments

Full-Text Search with DuckDB

https://peterdohertys.website/blog-posts/full-text-search-w-duckdb.html
151•ethagnawl•17h ago•31 comments