${DynamicText("About this genre (loading...)")}


## Implementation notes
This genre uses two algorithms, the [#inbox algorithm] and the [#outbox algorithm]. They may seem similar, but one is much easier than the other. Which one is it?

### Outbox algorithm
Finding the //outbox// for a list of points can be done easily. List all X coordinates, list all Y coordinates, and find the maximum and minimum for each. Add some padding to these coordinates and that's it. The //outbox//.

### Inbox algorithm
Finding the //inbox// for a list of points is more difficult. To understand it, please imagine a machine compacting the puzzle on all sides, over and over...
- we start with the big //outbox// and a backlog (initially empty);
- we list all 4 possible shrinking operations (L:left, U:up, R:right or D:down);
- these operations are added to the current sequence, without duplicates, yielding some future sequences;
	- duplicates are removed by discarding sequences not in alphabetical order
- the future sequences are added to the backlog, prioritised by maximal resulting box area
	- zero-area sequences can be discarded immediately
- we pick the top sequence in the backlog and shrink the outbox in that way, resulting in the largest candidate inbox;
- if this inbox contains no empty space, we stop there (we found it!) otherwise, we go back to the beginning.


##[inbox-outbox] Puzzles
### @AnuragSahay
W=6x6&L-BL=(4)4(6)5(8)8(4)12(3)4&L-WH=(8)2(24)4(10)15(6)4(12)10&G=inbox-outbox&A=Anurag&D=2024-07-24&F=3&N=1&T=Encircled

### @PinkHoodie
W=6x6&L-BL=(5)1(2)5(4)3(2)10(2)16&L-WH=(16)0(4)16(9)10(36)3(2)5&SSE=14URURUULDLDLDL3LUURRD14RDDLD15LUU&G=inbox-outbox&A=PinkHoodie&D=2024-07-25&F=1&T=Gone_Away
W=6x6&L=x10x2x2x21&L-BL=(6)7(4)1(4)13(6)7&L-WH=(8)2(8)15(15)2(16)14&SSE=2RR15URRRR2U5RRDDD&G=inbox-outbox&A=PinkHoodie&D=2024-07-26&F=2&K=Menderbug&T=Box_Holes


## Variants

### ´´territory-no-rectangle´´
V=territory-no-rectangle

W=6x6&L-BL=y6y9(6)4(4)1(6)9&L-WH=(20)0(4)14(25)4(6)3y14&G=inbox-outbox&V=territory-no-rectangle&A=PinkHoodie&D=2024-07-25&F=2&O=Territory_No_Rectangle&T=No_Box


## Acknowledgements and Changes
**2024-07-21** Thanks to @@どっかのだれか@@, the genre author, for making the [panels|../panels] of this genre!
**2024-07-24** Thanks to @AnuragSahay for sending a rollout puzzle and rule wording clarification suggestions!
**2024-07-25** A distinctive clue style was applied in collaboration with @@どっかのだれか@@ (who designed it) and @MartinEnder (who suggested the shape should resemble a box somehow). The symbol represents both the inner and outer rectangular boxes, and should immediately identify this genre!
**2024-07-26** A rollout puzzle was sent by @PinkHoodie, who also sent a good (passing) unit test for absent cells and remarked that number clues should be no lower than 2 (indeed) - thank you!
**2024-07-27** :::puzzletters @PinkHoodie sent 1 classic plus 1 puzzle using variant ´´territory-no-rectangle´´!
**2024-08-08** [Inbox-outbox] promoted to variant ´´inbox-outbox´´