Puzzle No. 500 – 9 Shady Masterminds [Special] [Marathon]

I thought quite a bit about what I wanted for my 500th puzzle here. There was a stage when I thought I’d just ignore the milestone and post something normal. Then I got a bit of an idea of a simple theme which might still give out a nice solve path with different logical deductions combining.

The puzzle that resulted from this idea is pretty narrow and quite difficult, according to my and Swaroop‘s test solving experiences. Still, I think its ended up being quite varied in the thinking required and I like how it turned out.

Unlike my usual approach of posting a single image, for this puzzle I am attaching a PDF instead. This PDF has 4 pages. The first page contains the puzzle. The 2nd and 3rd pages contain the rules (The length is just because there are 9 different puzzles to cover, but most of them are familiar and should just be a quick read-through). There are two newer puzzle types, and one variant which I couldn’t immediately find an example for, so I have added 6×6 examples for these three rule-sets. The remaining are all classics, so I’ve just linked to the respective page where I got the rules from, and you can visit these links if you want an example. If you are new here and haven’t seen those sites before, I suggest visiting them anyway for more great puzzles.

Here’s the PDF:

9 Shady Masterminds

Please let me know in the comments or by mail (prasanna16391@gmail.com) if you have any queries regarding the rules or any other issues.


IPC Preview – Practice, Solving Tips, Links

Update: Fixed the typo in Pentomino Kakuro. New PDF uploaded. No other change.

Update: There is an erratum published on the IPC site that says the 2×2 restriction applies to Happy Dots too. Since the practice puzzle in the PDF still gives a nice practice for placing the dots and forming regions, and only uses 2×2 regions minimally, it stays the same in the PDF. We’re sorry for the inconvenience. 

If you’re having trouble with some puzzles, seeing/adding to the discussion in the comments might help. (This also serves as a spoiler alert for those who want to work on the puzzles without help)

Right, took a while, but we’re finally there. If you’re still not aware, the Indian Puzzle Championship will be held on 7th July. Here are our (me and Swaroop) best efforts, with the main goal being to try to help the newer participants.

This PDF features –

1. Practice puzzles for B1, B2, C, D, E2, F1, F2, G2, I1, I2, J1, J2, K1, K2, L1, L2, M2.

2. Beginner-level solving tips for all the puzzles in the set.

3. Solutions to all the puzzles in the set.

4.  Links to other practice material, pattern guides, and other technical tips.

Link to PDF – Practice


Puzzle No. 228-229 : I’m just a Perennial Passenger

Firstly, I’ve forgotten to share the link to the Beginners’ Contest October, which has some big format changes. We have introduced an extended time feature that allows submissions until 17th October even if the test is started now! Note though, that after the 40 minutes, submissions will get 50 % of the points per grid. There’s also Instant Grading, and all the changes are announced in detail in the forum. The  test page can be found here.

Now back to a week ago. This isn’t much of a write up as much as “I have 2 Passenger Battleships and had to use them in these linking write-ups somehow”

Anyway, after the WPC there were the departures. I had one companion, Indian teammate, Rakesh Rai, following the same route back home. We had a one day stay in Zagreb first. Newcastle United vs Manchester United was scheduled later in the day, so after some sight seeing, we found a random bar where the match was being screened, and I saw it with some random British fans on a random visit, which was fun. Then I joined in some random party early in the morning for a while, and thats about all that happened in Zagreb. The flight back, like the flight to, stopped for an hour at Budapest, and then only did we go to Doha.

Doha was just a place to relax all day, as the climate wouldn’t suit me and the hotel, food, etc. was great. A day there and we finally made it back to India. Next time in Beijing will be a lot more easier in terms of travel at least. 😛

The 2 Passenger Battleships are below. The first one is far too big a grid, the 2nd  one should be alright. While creating these I found 0 an annoying and unnecessary ship,  as you can’t use the sums to get it, you either have to pack it in and force it or put in a given 0. I chose the latter as I don’t have much idea about packing. Thats why I got the first grid’s size wrong too. Anyway ,

Rules – Locate 12 passenger ships(rectangles of size 1×3 cells) horizontally or vertically in the grid. Ships cannot touch each other, not even diagonally. There is a different number of passengers on each ship, from 0 to 11. Numbers outside the grid indicate the sum of passengers on the ships in the corresponding row/column. Numbers given in the grid represent the number of passengers on the ship occupying the corresponding cell.


Puzzle No. 201-207 : Di… Practice Puzzles

Update – Thanks to Bram for pointing out that the Diayajilin actually works without the added arrows.

Right then. I haven’t posted all week since I’ve not been well. This basically meant I’m behind all my plans by 2 days, and seeing as I’m traveling for a week from Sunday, that leaves me really less time to do everything I want to. So anyway, this was the best I could force out in the little time I had. Some of the puzzles have quick fixes, one of the Yajilins has a segment given, and there are some other places where I decided to experiment a little like the Division fleet. Anyway, practice is practice, and for what its worth, here they are. It’d be weird to post these after the test anyway, and weirder to just put them away. You can find some others from other sources on the Discussion thread for Di… Anyway, I actually made a Diagonal variant of Yajilin a long while ago here. Its got some different formatting but I think the rules are pretty much the same. I must thank my testers Tom and Murat Can Tonta for getting this done so fast. I have tons of things left to do. I shall resume posting on the 7th/8th September mostly, and will mostly have a good announcement lined up too 🙂

So in order, the below puzzles are – Diayajilin(2), Disposition(with Fleet), Diversion, Diversion without Borders, Division(with Fleet), Dioxides(with 21 Os atoms, though I don’t see how that affects the solve anyway). All rules taken from the IB here. Unlike my usual style, all rules are below the respective puzzles.


Diayajilin – Blacken some cells so that you can draw a single closed loop through all remaining white cells. Black cells cannot be adjacent to each other. The loop cannot touch or cross itself. Each number in the grid shows how many black cells can be seen in the direction of the arrow. Numbered cells cannot be blackened. Addendum – A loop segment is given in one of them. Also, clues pointing in two directions indicate that many number of black cells for each of the directions, and not the sum of them.


Disposition – Place the given fleet following the grid lines. Ships cannot touch each other even diagonally and cannot occupy cells with digits. Each number in the grid shows how many ships (Rectangles or Squares) are located in the horizontally, vertically and diagonally adjacent cells. Addendum – “?” is a digit not given to you, so it basically just means that there’s no ship segment on that cell.

Diversion – Each number in the grid shows how many mines are located in the horizontally, vertically and diagonally adjacent empty cells. The object is to reveal all the mines in the grid, providing that a cell can contain only 1 mine. Mines cannot occupy cells with digits.

Diversion without Borders – Cut the grid into 1×2 rectangles. Each number in the grid shows how many mines are located in the horizontally, vertically and diagonally adjacent empty cells. The object is to reveal all mines providing that a 1×2 rectangle can contain only 1 mine. Mines cannot occupy cells with digits.

Division – Place the given fleet and 20 mines into the grid. A cell can contain only 1 mine. Each number shows how many parts of ships OR how many mines are located in the horizontally, vertically and diagonally adjacent empty cells. Mines and ships cannot occupy digits. Ships cannot touch each other and cells with mines, not even diagonally.

Dioxides – Place letter “s” in 21 cells with letter “O”. Cells with Os(Osmium atom) cannot touch each other, not even diagonally. These, along with 2 other oxygen atoms O, will form 21 Osmium dioxides with either a 180 degree turn at the Os atom, or a 90 degree turn. i.e. atoms can’t be connected diagonally. Addendum – Test puzzle will have 27 wherever 21 is above.

Puzzle No. 193 : Spiral Battleships(s) [LMI Practice puzzles again]

Right. The first one of these is pretty easy. I just did it to familiarize myself. The 2nd one, I decided to experiment with the layout a little, as the various features of the variant can still be explored with different layouts as long as the numbers have a path to follow. So here they are. I’ve given the fleet below which is common for both puzzles. Of course, the labeling of the fleet shall be determined over the course of the solve, as the rules show.

Rules(from the AO competition IB again) –

1.Locate the given fleet in the grid. The ships cannot touch each other, not even diagonally.
2.Clues outside the grid indicate the sum of ship segments in the corresponding directions.
3.Ship segments are numbered from 1 to 20, starting from the entrance of the spiral and moving towards the center.

Rated Easy and Medium respectively.


Puzzle No. 193 – I

Puzzle No. 193 – II

10-ship fleet

Puzzle No. 180 : Yajilin/Battleships

First of all I shall bore you with all the contests that are happening/coming soon.

1. Sudoclones on LMI : Going on now. Authored by Sylvain Caudmont.  A bunch of sudokus where the givens are cloned but the solves shall be different. Fun eh? This marks the first time I haven’t given a contest the minute its been there to give. There is in fact one more day remaining, so like me, if anyone hasn’t found time till now, go on and compete 😉

2.  Times Sudoku Championship : Shall go on over the month of July, for all Indians, with regional rounds in 4 cities in India, except the Bangalore one got over today. But since it came on the TOI, you don’t need my blog telling you that hopefully. I’m not sure yet about the finals, but the Mumbai round shall be very interesting and competitive, and I hope I can get through it to the finals.

3. ??? : Coming later this year. You know nothing about it. You shall know nothing more about it. Except that it is one of the reasons I haven’t been able to post as regularly here(with due apologies again).

Today’s puzzle was made 2-3 days back but I never got time to get it tested and posted. Its a good thing I did wait to get it tested, as it had a slight uniqueness issue I had missed.

Rules for Yajilin. Instead of just filling in isolated cells according to the clues, there’s a fleet of ships given(well, more like a shape bank here since I don’t think you’ve seen some of these ships in regular Battleships) which have to be placed in the grid to form the cells the loop does not pass through.  These shapes cannot touch each other even diagonally, but can be rotated/reflected before being used in the grid.

Rated : Hard due to the start, almost easy after that though.


Puzzle No. 180


Its as easy as IPC (practice puzzles) (Part 1?)

I’m not numbering these simply because I don’t want to rush to 200 as I’m not ready with an idea for that 😛

These are puzzles that can be used for practice for the Indian Puzzle Championship and you can refer to the Instruction booklet provided on that link for better understanding of the rules with examples.. These are mostly around the difficulty I’ve generally seen at IPC, i.e. , around easy for experienced solvers, somewhere from medium to more for the first time solvers.

I’ve concentrated on types that are not on my blog already. You can see previous posts for Masyu, Slitherlink, Tapa, Graffiti Snake here and here.  I wasted a lot of today making a Liar Slitherlink only to find that I’d made a stupid error right at the start. Thats why only 6 puzzles, I hope to have either a Liar Slitherlink, or some other puzzles ready tomorrow, and Friday. Lets hope I get them working 😉

Anyway, obviously the heading suggests what I’m gonna open with.

As Easy As IPC

Enter the letters I, P and C, so that each letter appears exactly once in every row and column. Some cells will remain empty in each row and column. The letters outside the grid show the first seen letter from that direction.










Tapa Borders

Paint some empty cells to create a continuous wall. Numbers in a cell indicate the length of painted blocks on its neighboring cells. If a cell has more than one number, there must be at least one white cell between the blocks. No 2×2 squares can contain only painted cells. The borders between some cells may be thick or non existent. A thick border separating two cells means one is painted and one is not. Lack of a border means the 2 cells are either both painted or both white.












Locate the indicated fleet in the grid. Each segment of a ship occupies a single cell. Ships can be rotated but cannot be reflected. Ships do not touch each other, even diagonally. Some ship segments, or sea cells without ship segments, are given in the grid. The numbers outside the grid reveal the total number of ship segments in that row or column.

Note : The letters A, B, C may be equal or unequal, the only constraint I’ve added is that their sum equals 4. This is just to introduce first timers to the summing up logic that can be used sometimes in this type.








Locate a snake in the grid, whose head and tail are given. The snake does not touch itself even at a point. Numbers outside the grid indicate lengths of snake segments in the corresponding direction.











Star Battle 

Place the given number of stars in each row, each column and each region. Stars cannot touch each other, not even diagonally.











Colored Star Battle

I’m new to this type myself even as a solver, so the puzzle may leave a lot to be desired. Sorry about that. Although it should be an easy warm up for first timers, I do think the difficulty of the IPC one will be higher given the high points. Anyway,  Place the given number of stars in each row, each column and each region. Similarly colored stars cannot touch each other, not even diagonally. Some stars may be given.