frontpage.
newsnewestaskshowjobs

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: Free car spec db to defeat the paywalls

https://openlaborproject.com/
1•chackleman•3m ago•1 comments

Madison Square Garden Sues Wired Magazine over L.G.B.T.Q. Tracking Report

https://www.nytimes.com/2026/07/18/business/media/msg-entertainment-sues-wired-magazine.html
1•ChrisArchitect•3m ago•0 comments

How Word Count Is Important for Social Media Posts

https://medium.com/@thesuperrepemail/how-word-count-is-important-for-social-media-posts-87372645377c
2•rajsuper123•15m ago•0 comments

William Gaddis and William H. Gass: A Literary Conversation and Reading (1995)

https://www.92ny.org/archives/william-gaddis-and-william-h-gass-a-literary-conversation-and-reading
1•ofalkaed•20m ago•0 comments

Trump Media pitched $100K monthly fee for fastest feed of US president's posts

https://www.reuters.com/business/media-telecom/trump-media-pitched-100000-monthly-fee-fast-feed-u...
3•geox•22m ago•1 comments

Disney Has Started Feeding Your Kids AI Slop

https://kotaku.com/disney-has-started-feeding-your-kids-ai-slop-2000717222
3•wslh•29m ago•0 comments

Lawyers risk being sued for failing to use AI

https://www.legalcheek.com/2026/07/lawyers-risk-being-sued-for-failing-to-use-ai/
3•Tomte•30m ago•0 comments

LLM-Integrated Multivariable Calculus Course

https://calculus.academa.ai/
3•sinaatalay•36m ago•1 comments

Topographical Collection of King George III

https://www.flickr.com/photos/britishlibrary/collections/72157719509637544/
1•Eridanus2•36m ago•0 comments

XRPLink – Cryptographically Verified XRP Payment Receipts, Powered by Flare FDC

https://github.com/joverman/xrplink
1•joverman•49m ago•0 comments

FDA approves new kind of cholesterol pill

https://www.fda.gov/news-events/press-announcements/fda-approves-first-oral-pcsk9-inhibitor-lower...
2•mgh2•51m ago•0 comments

Useless Use of Cat Award

https://porkmail.org/era/unix/award
1•gregsadetsky•1h ago•1 comments

Novo Space builds modular computers for satellite constellations

https://runtimewire.com/article/startup-spotlight-novo-space-builds-modular-computers-for-satelli...
1•ryanmerket•1h ago•0 comments

Gaming Sickness and Its Impact on Players' Experiences with Games

https://dl.acm.org/doi/10.1145/3670653.3677494
2•BiraIgnacio•1h ago•0 comments

I built a browser-based P2P file transfer tool using WebRTC

https://airdows.com/
2•SamOkampo•1h ago•1 comments

Jordan Ellenberg explains how geometry helps us understand the world

https://www.cbc.ca/lite/story/1.6448326
1•colinprince•1h ago•0 comments

Retry is not a loop, its a data structure

https://siddhantkhare.com/writing/retry-is-not-a-loop
2•meetpateltech•1h ago•0 comments

Association Between Low/No-Calorie Artificial Sweeteners and Cognitive Decline

https://www.neurology.org/doi/10.1212/WNL.0000000000214023
2•corvad•1h ago•0 comments

PersonalDrive: Personal Cloud Storage

https://personaldrive.xyz/
1•thunderbong•1h ago•1 comments

Implementation of "Writing a C compiler" in Zig

https://github.com/igor84/wcc
2•rguiscard•1h ago•0 comments

Toyota pump tech could be key to hydrogen-combustion practicality

https://www.autocar.co.uk/car-news/technology/toyota-pump-tech-could-be-key-hydrogen-combustion-p...
1•breve•1h ago•0 comments

Track you Claude Code usage in dollars

https://www.claudeusage.com/leaderboard
2•bazarkua•1h ago•1 comments

Seamless iPad (or any device that can run a web browser) drawing into org-mode

https://github.com/larrasket/org-pad.el
1•lr0•1h ago•0 comments

China cracks down on AI companions, forcing millions to break up

https://www.abc.net.au/news/2026-07-19/china-cracks-down-on-artificial-intelligence-companions/10...
3•defrost•1h ago•1 comments

Archaeologists found Homer's Iliad inside a 1,600-year-old Egyptian mummy

https://www.sciencedaily.com/releases/2026/07/260713084918.htm
4•NordStreamYacht•1h ago•0 comments

IceCream – Never use print() to debug again

https://github.com/gruns/icecream
1•gregsadetsky•1h ago•0 comments

Claude Is Painful

5•kderbyma•1h ago•3 comments

Deepsec

https://github.com/vercel-labs/deepsec
2•handfuloflight•1h ago•0 comments

AI Mania Is Eviscerating Global Decision-Making

https://ludic.mataroa.blog/blog/ai-mania-is-eviscerating-global-decision-making/#fnref:3
40•subset•2h ago•5 comments

Prompt Injection Attacks Are Thwarting AI Hacking Agents

https://arstechnica.com/security/2026/07/now-defenders-are-embracing-the-prompt-injection-too/
1•sbulaev•2h ago•1 comments