This is the archive of the old posts from Djape .Net, more or less as they used to be. Please go to djape.net to see the new website.

Binary Puzzles

Here is another novelty: Binary Puzzles, also known as TAKUZU. Binary Puzzles are played on square grids of any even size: 6×6, 8×8, 10×10 etc. Your goal is to fill the grids with 0s and 1s, following these simple rules: 1. There can be at most two 0s or at most two 1s next to each other, horizontally or vertically. So, 00 and 11 are ok, but 000 and 111 are not ok; also, 010 and 101 are totally fine. 2. There must be an equal number of 1s and 0s in each row and in each column. 3. Two columns cannot be completely the same. Neither can two rows be the same. And that’s all!

Binary Takuzu Puzzle: 12×12 WARNING: DIFFICULT!

Click on the puzzle thumbnail to access the puzzle.
Takuzu: Binary Puzzles book

How to solve Binary Puzzles

Well, the basics are very simple and follow directly from the rules just explained. Let’s see these examples:
?00?1?1
From 1st rule we conclude that the first and second “?” must be 1. Also, from the same rule, the third “?” must be a 0. That’s easy.
?10110?101
There are already five 1s in this row of 10 cells. Therefore, in order to abide by the 2nd rule, the remaining two spots must be filled with 0s!
0101100101
1010
010110xxx01
This is only a part of a puzzle. See how first row is completed and the 3rd row is almost the same as the first one. If x=0, then because of the 2nd rule xx=1, but then the 1st and the 3rd rows would be completely the same! Therefore, x=1 and xx=0! Finally, let’s look at a slightly more complex position:
100100?
Here, there are already four 0s filled in. There can be only one more 0 in this row! Can the “?” be “0”? No! Why? Because the three blank cells would all have to be 1 and since they are all adjacent, this would be against the 1st rule. Therefore, there must be a “1” in place of the “?”. Got it? Every time there is only one occurrence of a digit missing in a row, check where it can or cannot go! What do you think?
Posted in Free sample puzzles, Puzzle variants | Tagged , , , , , , , , | 5 Responses

Number Search Puzzle

Here is a nice and simple puzzle for you: NUMBER SEARCH. It’s like word search puzzle but with numbers. Search for the numbers listed below the grid and find them in the grid. Search for them in any of the 8 directions (horizontal, vertical, left diagonal, right diagonal and each of them in forward and backward direction). The rules are simple but finding the numbers is not easy! What do you think?

Big Number Search puzzle: 20×20

Click on the puzzle thumbnail to access the puzzle.
Number Searches Very Large Print Book

And it’s also available in PDF format. Click here to download Number Search in PDF format.
Posted in Free sample puzzles, Puzzle variants | Tagged , , , , , , | 2 Responses

Futoshiki

The rules of Futoshiki are very simple: 1. The grid is square and can be of any size. Use numbers 1 to the size of the grid to solve the puzzle. 2. Numbers cannot be repeated in a row or column. All numbers must appear in each row and in each column. 3. The “more or less” constraints across the grid must be satisfied. The symbols < and > tell you which of the two numbers is greater of smaller. So, there are no “nonets” in Futoshiki as there are in Sudoku. However, most of the Sudoku solving techniques can be used: singles, subsets and even X-Wing and Swordfish!

Free Futoshiki puzzle: difficulty BRAIN

Click on the puzzle thumbnail to access the puzzle.
Futoshiki plus gifts

Please tell me how do you like this puzzle.
Posted in Free sample puzzles, General | Tagged , , , , , , , , , | 1 Response

Super Samurai Sudoku 13 grids

Some people consider Sudoku Samurai puzzles too big; some other people prefer even bigger puzzles. If you belong to the second category, here is an overlapping sudoku variants puzzle for you: 13 grid Sudoku (Gattai-13) laid out in a quadruple Samurai Sudoku format. Essentially, there are 13 Sudoku sub-puzzles which overlap the same way as in Samurai Sudoku. So it is like having 4 Samurai Sudokus on top of each other! Or, 2 Sudoku Harakiri puzzles side by side!

Super Samurai 13 grid Sudoku

Click on the puzzle thumbnail to access the puzzle.
Super Samurai Sudoku 13 grids

What do you think? Should I make them even bigger? πŸ™‚
Posted in Free sample puzzles, Samurai sudoku, Sudoku Variants | Tagged , , , , , , , , , , , | 6 Responses

Killer Sudoku on Saturdays!

I should’ve announced this before, but was too busy making the sudoku variants book. So… As of today, every Saturday on the Killer Sudoku page a Killer Sudoku 10×10 will be posted! Almost 8 years after I started posting daily killer sudokus, now there will be a Sumdoku puzzle on Saturdays, too! Remember to add the 0 too when calculating sudoku sums! The rule of 45 still applies. What do you think of these Killers?
Posted in Killer Sudoku | Tagged , , , , , , | 1 Response

Killer Sudoku 10×10

When was the last time I posted a Killer Sudoku variant puzzle for the first time? I can’t remember. Well, nearly 8 years (I’m a bit slow, you know) after publishing first Killer Sudoku, it occurred to me that there is no reason not to add the 0 into play. So… ladies and gentleman… a world premier (or is it?)…

Killer Sudoku 10×10

– use digits 0 to 9 to solve this one! Click on the puzzle thumbnail to access the puzzle.
Fiendish Killer Sudoku Book

How to solve this? Well, use exactly the same techniques as you would normally. The rule of 45 still applies – we are only adding the 0! However, be careful when analyzing cage combinations – things are now quite different and there are more options for each cage sum. And don’t be surprised when you see a sum of “2” over 2 cells. 1+1 is not an option (no repeats, of course), but there is now another possibility: 0+2! What do you think? πŸ™‚
Posted in Free sample puzzles, Killer Sudoku | Tagged , , , , , , | 14 Responses

Pirates’ Games

This is not a puzzle related post. πŸ™‚ It’s a brain teaser (I used to post brain teasers years ago). I’ve been studying game theory lately and wanted to share one “classic” problem of this discipline with you. See if you can solve it by yourself. Post your solution as comments below this post. So… here we go…

Pirate Games

Five pirates have obtained 100 gold coins and have to divide up the loot. The pirates are all extremely intelligent, treacherous and selfish (especially the captain) each wanting to maximize the number of coins that he gets.
It is always the highest ranked pirate who proposes a distribution of the loot. All pirates vote on the proposal, and if half the crew or more go “Aye”, the loot is divided as proposed.

Read More »
Posted in General | Tagged , , , | 14 Responses

Odd Even Sudoku

Merry Christmas to all who celebrate this day! πŸ™‚ As a small gift for you, I’ve prepared an odd-even sudoku variation puzzle. It’s not the first odd even puzzle I ever posted, but it is the first plain odd even sudoku. And to spice things up a little bit, this is a very difficult odd/even sudoku! It requires you to use the swordfish solving technique! Usually, odd even puzzels are quite easy, but this particular one is rather fiendish! It starts off easy, but then… well, see it for yourself! πŸ™‚ Oh… and as you may have noticed… all puzzles are now “facebook free” and they will stay that way, for as long as those folks who do have facebook keep clicking on the “like” buttons. It is not required any more, but it would be nice if you did “like” the free puzzles you download! πŸ™‚ Have a nice one, folks! πŸ™‚

Odd Even Sudoku for December 25, 2012 – Difficulty INSANE

Click on the puzzle thumbnail to access the puzzle.
Loco Sudoku Puzzle Book Cuckoo Wacky Quirky

Posted in Free sample puzzles, Sudoku Variants | Tagged , , , , , , , , , , , | 4 Responses

Sudoku Variations

I’ve created numerous variations of Sudoku puzzles. Here is a list of some of them. View a more comprehensive list on the Sudoku Variants page. And then you can find even more of them in the Sample Puzzles category. You can also see my Sudoku Variations books.

Diagonal Sudoku book

Diagonal Sudoku
Jigsaw Sudoku book, volume 4

Jigsaw Sudoku
Flower  Sudoku and Outside  Sudoku

Flower Sudoku
Outside Sudoku and its variants, vol 2

Outside Sudoku
Non Consecutive Sudoku book, volume 2

Non Consecutive Sudoku
Double Samurai Harakiri Sudoku 99 puzzles

Sudoku Samurai
Sudoku Straights, where Poker meets Sudoku

Sudoku Straights
Tridoku Triangular Sudoku volume 2

Tridoku
Killer Samurai Sudoku, 100 puzzles, volume 4

Killer Samurai Sudoku
Killer Sudoku Compendium

Killer Sudoku
Posted in Sudoku Variants | Tagged , , , , , | 1 Response

How to solve Diagonal Sudoku X

I realize that I’ve never posted two sudoku solving techniques which are specific to Diagonal Sudoku puzzles.
Diagonal Sudoku book

Here they are.

Diagonal and nonet interaction

This one is a simple extension of the “row/column and nonet interaction technique”. Just look at this sample puzzle which has been solved using the standard techniques up to this point: Focus on the number “4” in the bottom left nonet. Out of three unsolved cells, the number 4 can go into only two of them: R7C3 and R9C1. As it happens, both of those two cells are on the diagonal. Can you see what I mean? Well, when that happens, it means that the number 4 cannot go anywhere else on the diagonal, outside of this nonet. Get it? Again: 4 is a candidate in one nonet ONLY in cells which belong to a diagonal. Whichever one the 4 goes into, it will be on a diagonal and therefore, we can eliminate the 4 from the rest of this diagonal, outside of the nonet. So… now we look at the rest of this diagonal and find that in the top right nonet, number 4 can be eliminated from one unsolved cell (R3C7) of the diagonal, which in turns effectively solved this cell – since it can’t be 4 it must be 2 (the only remaining candidate for that cell). Get it?

Diagonal Sudoku Crossover technique

This technique is somewhat similar to the previous one. Let’s look at another sample puzzle. First, focus on the main diagonal. Number 9 has to be somewhere on this diagonal and as you can see, the only two options are R1C1 (upper left corner) and R9C9 (bottom right corner). In such case, when there are only two cells on a diagonal that could potentially hold a number, we can apply the Crossover technique. How?
Well, let’s assume that number 9 goes into R1C1. In that case, 9 would be eliminated from the rest of R1 and C1. If 9 went into R9C9, it would be eliminated from R9 and C9. Either way, wherever 9 goes, it would be eliminated in the intersection of those rows and columns, in other words, where the imaginary lines, two horizontal and two vertical, cross. So, 9 can be eliminated from R1C9 (and also from R9C1 but that cell is already solved), which solves that cell: R1C9 = 3 (the only other option). Hope this was helpful and clear enough. πŸ™‚
Posted in Solving tips, Sudoku Variants | Tagged , , , , , , , , , | Leave a comment
eXTReMe Tracker