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Logic Masters India - Screen Test 1

After the success of sudoku and puzzle tests on Logic Masters India, here comes a new dimension - 'Screen Test'. Screen Tests are part of most, if not all, World Puzzle Championships. In Screen Tests, the puzzles are displayed on the screen; participants solve the puzzles by looking at the screen. Typically the answer to the screen test puzzles is a number or a letter or at max few words.
LMI Screen Test is designed based on WPC Screen Test philosophy, to make screen tests available to more puzzle solvers. The first Screen Test was held on 4th/5th/6th December, 2010.
It was organised by Deb Mohanty and me!

Download Screen Test Guide
View Screen Test Homepage
View Examples
View Forum


1. Martin Merker (Germany) - 1477
2. Thomas Snyder (USA) - 1450
3. Hideaki Jo (Japan) - 1394
4. Philipp WeiƟ (Germany) - 1386
5. Palmer Mebane (USA) - 1376
6. William Blatt (USA) - 1363
7. Kota Morinishi (Japan) - 1352
8. Masashi Sakata (Japan) - 1350
9. Sebastian Matschke (Germany) - 1346
10. Psyho (Poland) - 1339

Best Indians

16. Keshava Murthy - 1220
23. Rajesh Kumar - 1063
26. Rishi Puri - 1038
31. Ritesh Gupta - 985
44. Prasanna Seshadri - 878

There were a total of 183 participants from 35 countries.

Complete Results

Screen Test 1 is finally over and so is one hectic weekend. It was an amazing experience! Right from building on the concept to its final implementation, it was like one joyful ride. I think organising a 30-minute Screen Test is more difficult than a 2-hour test. Trust me on this! Creating enjoyable puzzles, screen-type puzzles, solvable puzzles, with varying difficulty, deciding the timing of each puzzle, etc. required a lot of thinking. Somehow Deb and I managed it. Then came the most important part. The website. Deb designed the whole thing with me giving some small inputs. When we thought we were ready with it, it had to be tested.
Special thanks to Rajesh Kumar, Rakesh Rai, Rishi Puri, Ritesh Gupta and Tejal Phatak for removing time and solving the test beforehand and giving feedback on the interface.

I am quite satisfied with the Screen Test. I dont think there has been one earlier (WPC-style), but I may be wrong. I'm glad most of you liked the puzzles and overall enjoyed the test.
Feedback of players

About the puzzles... well... the feedback statistics say that many puzzles were solvable on screen but not all. I agree some puzzles were not solvable on screen, but we decided to keep few difficult puzzles so that even the best players get tested :-)

There were some very interesting statistics of puzzles that caught my eye.
Mazes was undoubtedly the easiest puzzle, solved correctly by maximum players with the minimum average time.
I was surprised to find Cell Sudoku solved by the least number of people. That kind of grid has only one solution. Maybe players didnt find 45 seconds enough to notice it.
Missing Words was a tight puzzle. You needed to be quick to make it within 60 seconds.
Correct XV was tough, no doubt. If you see the puzzle leisurely, you should be able to find out the errors without actually solving it.
For Mastermind, I'm sure most people would've checked which solution matches to the puzzle. It is quicker than solving the mastermind puzzle.
The last 4-5 puzzles were deliberately made a little difficult, to test players who zoomed through the first 20 puzzles.
We kept Brilliant Colours at No.25 to have a colourful and bright ending :-)

Thank You all for participating and making Screen Test 1 a big success. Please give your feedback and comments as they are most welcome.
Looking forward to seeing you all at Screen Test 2, where I hope to participate! :-)

Indian Puzzle Championship - November 2010 Monthly Test

Logic Masters India announces the November monthly test 'FLIP'.
The author of the puzzles are David Millar.


Download Instruction Booklet
Download Puzzle Booklet
Password is FLIP11PILF
Download FLIP Special Booklet

The list of puzzles that appeared in the test are:

1. Flip And Fill Sequence
2. Flip Shape Sudoku
3. Flip Strips
4. Flip Mirror Sums
5. Flip Mirror 0-2-5
6. Flip Slitherlink
7. Flip Every Second Breakpoint (by Deb Mohanty)


1. Thomas Snyder (USA) - 644
2. Hideaki Jo (Japan) - 644
3. Nikola Zivanovic (Serbia) - 491
4. Jana Tylova (Czech Republic) - 459
5. Kota Morinishi (Japan) - 451
6. Michael Ley (Germany) - 443
7. Psyho (Poland) - 435
8. Shinichi Aoki (Japan) - 402
9. Stefano Forcolin (Italy) - 390
10. Rakesh Rai (India) - 370

Best Indians

10. Rakesh Rai - 370
14. Rohan Rao - 367
20. Keshava Murthy - 341
21. Rishi Puri - 338
23. Jaipal Reddy - 337

Complete Results

There were totally 98 participants.

Very nice set of puzzles. Conceptually brilliant! I liked the ESB, Slitherlink and Mirror 0-2-5. Great job David.
I felt the test could have had more puzzles to add to the positivity.
Congrats to Thomas Snyder and Hideaki Jo, who topped the test by a huge difference from others.

Puzzle No.335

Puzzle: Fence
Source: Indian Puzzle Championship 2010



Puzzle No.334

Puzzle: Classic Sudoku
Author: Fred Stalder



Puzzle No.333

Puzzle: Sequence Sudoku
Author: Rohan Rao



Puzzle No.332

Puzzle: Irregular Sudoku
Source: Indian Puzzle Championship 2010



Puzzle No.331

Puzzle: Divisible By Three Sudoku
Source: Indian Puzzle Championship 2010



Rules of 'Divisible By Three Sudoku'

Place numbers in the grid such that each row, column and 3x3 box contain the numbers 1 to 9. In each 3x3 box, the number created by three horizontally or vertically adjacent digits must be divisible by 3.



Puzzle No.330

Puzzle: Skyscrapers
Source: Indian Puzzle Championship 2010



Puzzle No.329

Puzzle: Light It Up
Source: Indian Puzzle Championship 2010



Puzzle No.328

Puzzle: Arrows
Source: Indian Puzzle Championship 2010



Rules of 'Touchy Sudoku'

Place numbers in the grid such that each row, column and 3x3 box contain the numbers 1 to 9. Each digit touches, vertically or horizontally at least one consecutive digit.



Puzzle No.327

Puzzle: Classic Sudoku
Source: Indian Puzzle Championship 2010



Puzzle No.326

Puzzle: ABC Connection
Source: Indian Puzzle Championship 2010



Solving Classic Sudoku: 'Single Position'

This is the easiest technique of finding out a number. Select a row/column/box (preferably with many given numbers) and find out the numbers remaining. Using other given numbers, try to find a unique position of one of the remaining numbers of the chosen row/column/box.

Take a look at Puzzle No.144. We select the 5th column as it has 4 given numbers. Since there is a '1' in the box above the centre box and the box below the centre box (which should be identified visually), let us try to find the position of '1' in the 5th column.

All possible positions of '1' in the 5th column are marked in green.

'1' cannot be placed in the top two and bottom two cells of the 5th column because '1' will then be repeated in a box as there is already a '1' in the two boxes.

There is only one unique position remaining for the '1' in the 5th column.

Other Solving Techniques

Solving Techniques

With a lot of people asking me questions like 'How do you solve this puzzle?', 'Are there any tricks in solving this sudoku?', 'How do players solve so fast?', etc. I have decided to start sharing some solving techniques. I will post some solving techniques of common puzzles and sudokus and then move on to other more complex ones. Below is the list of solving techniques that I have posted till date.
Feel free to comment and give me feedback. If you want some solving techniques of a particular puzzle, you may ask here and I will try to post some tips :-)

Hope you like and benefit from them :-)

Sudoku Solving Techniques
Most sudokus (apart from irregular ones) are in the standard classic form, so the techniques of solving a classic sudoku apply to other sudokus with 3x3 boxes too.

Classic Sudoku
Technique 1: Single Position
Technique 2: Single Candidate
Technique 3: Candidate Lines
Technique 4: Two Pairs
Technique 5: Multiple Lines
Technique 6: Naked Pairs/Naked Triplets
Technique 7: Hidden Pairs/Hidden Triplets
Technique 8: X-Wing

Killer Sudoku
Technique 1: Unique Combinations

Odd-Even Sudoku
Technique 1: Section Solving

Puzzle Solving Techniques
Every puzzle has its own techniques but you may find some similarity between similar puzzles like Loop Puzzles, Connection puzzles, etc.

Along The Lines
Techhnique 1: Singular Cells

Technique 1: Outside Sums

Black And White
Technique 1: Edge Connection
Technique 2: Opposite Pairs

Technique 1: Unique Combinations
Technique 2: Minimax-Maximin
Technique 3: Overlapping Cells

Star Battle
Solved Example 1

Technique 1: Elementary Beginnings

I have named all the techniques, for consistency and convenience, which may differ from what you know.
Enjoy and look for more techniques coming soon!

Indian Sudoku Championship - November 2010 Monthly Test

Logic Masters India announces the November Monthly Test 'Renban Groups'. It was held on 13th-14th November, 2010.
The author of the puzzles are Zafer Huseyin Ergan.


Download Instruction Booklet
Download Puzzle Booklet
Password is 123renBAN456
Download Solution Booklet

The list of sudokus that appeared in the test are:

1. Classic Sudoku
2. Shifted Sudoku
3. Diagonal Sudoku
4. Argyle Sudoku
5. Antiknight Sudoku
6. Non-Consecutive Sudoku
7. Symmetric Unequal Sudoku
8. No Touch Sudoku
9. Chaos Sudoku
10. Diagonally Non-Consecutive Sudoku


1.  Rishi Puri (India) - 592
2. Fred Stalder (Switzerland) - 570
3. Jakub Hrazdira (Czech Republic) - 565
4. Rohan Rao (India) - 561
5. Jason Zuffranieri (USA) - 559
6. Hideaki Jo (Japan) - 543
7. Chen Cen (China) - 538
8. William Blatt (USA) - 529
9. Nikola Zivanovic (Serbia) - 517
10. Kota Morinishi (Japan) - 516

Top Indians

1. Rishi Puri (India) - 592
4. Rohan Rao (India) - 561
27. Rakesh Rai (India) - 409
30. Amit Sowani (India) - 393
35. Tejal Phatak (India) - 385

Complete Results

There were totally 167 participants.
Congrats to everyone!

Thanks to Zafer for this very exciting contest. The puzzles were very well-made and the use of the Renban groups were very neat and logical. I liked the 6x6 No Touch, 9x9 Shifted and Chaos the best of the lot.
Looking forward for the next contest :-)

UKPA Sudoku Contest 1

The 1st UKPA Sudoku Championship was held on 6th-7th November, 2010.
The author of the puzzles are Tom Collyer.


Download Instruction Booklet
Download Puzzle Booklet
Password is gTP97rtE1

The list of sudokus that will appear in the test are:

1. Classic Sudoku
2. Diagonal Sudoku
3. Irregular Sudoku
4. Non-Consecutive Sudoku
5. Surplus Sudoku
6. Tens Sudoku
7. No Tens Sudoku
8. No Touch Sudoku
9. Toroidal Sudoku
10. Islands Sudoku
11. Touchy Sudoku
12. Kurve Sudoku
13. Killer Sudoku
14. Arrow Sudoku


1. Florian Kirch (Germany) - 256
2. Yuhei Kusui (Japan) - 242
3. Hideaki Jo (Japan) - 240
4. Alien (USA) - 220
4. Ours Brun (France) - 220
4. Chen Cen (China) - 220
4. Don3232 (Taipei) - 220
4. Jakub Ondrousek (Czech Republic) - 220
9. Ulrich Voigt (Germany) - 215
10. Nikola Zivanovic (Serbia) - 210

Indian participants

11. Rishi Puri (India) - 195
13. Rohan Rao (India) - 185
37. Tejal Phatak (India) - 120
45. Jaipal Reddy (India) - 110
45. Neeraj Mehrotra (India) - 110

Complete Results

There were totally 120 participants.
Congrats to everyone!

Very nice set of puzzles. I enjoyed solving Sudoku Islands and Surplus Sudoku. Killer was superb while the common variations were full of wonderful designs and shapes. Thanks for the puzzles and I had a good weekend :-)
Hope to see more in future.

Rules of 'No Ten Sudoku'

Place numbers 1 to 9 in the grid such that each row, column and 3x3 box contains each number exactly once. The sum of the numbers in two adjacent cells cannot be ten.



World Puzzle Championship 2010

The 19th World Puzzle Championship was held from 24th-29th October, 2010 in Warsaw, Poland.

Official Website

Team India
Rohan Rao (Mumbai)
Rajesh Kumar (Bangalore)
Tejal Phatak (Mumbai)
Aman Pruthi (Pune)

This was my 2nd WPC and I was hoping to improve my 2008 performance (68th).
The complete IB was released quite late, after the four of us were on our flight to Poland. So it deprived us (and others) some precious practise time. The IB had some errors which could have been avoided. I was surprised when those mistakes weren't corrected even in the final print of the IB which every partipant received. That was when this 'Wavy' (As I call it, due to its unpredictable highs and lows) WPC began.

24th October
We arrived in Poland and experienced temperatures of around 8-deg C. It is quite cold for Indians which explains why Tejal wore 5 layers of clothing. After an hour's drive we reached Hotel Kuznia Napoleonska. After relaxing and taking a nap, we went for the Welcome Party. As usual, food was a big problem, especially for me, being a vegetarian. Long live bread, butter and salads!
The Welcome Party was shorter than I expected it to be, nonetheless, it was nice meeting up and chatting with the best puzzlers across the globe.

25th October
We had a city tour, went around few places with a guide and did some shopping. I was fast asleep on the way back to the hotel. Stupid jetlag.
The Q&A session after dinner was long as expected. There were quite a few doubts and incomplete instructions regarding the booklet. I guess the Polish team didn't do their homework well.

26th October
Competiton day! It started off on a high with Round 1 in which Andrey Bogdanov (Russia) was the only player to complete the round. I made an unforgivable mistake in Round 2. I forgot to solve the sudokus. It was on the last page and I completely missed it. I messed up a couple of other puzzles too resulting in a very poor score. I felt a little low after this round and was a bit off-colour throughout the remaining rounds. I managed to coverup some of those points by the end of the day. Anaconda, the deadly team round was a disaster. We had little team coordination and the fact that Aman and Tejal dislike Snake puzzles, made it even tougher for us. We were last in this round :-(
Puzzles were great and fun to solve. Thumbs up from me.
The day ended positively with Vladimir Portugalov (Belarus) and Thomas Snyder (USA) sharing their views and ideas of creating and solving some difficult puzzles. I think this was the best part of WPC 2010.

27th October
The remaining rounds went smoothly for me. No errors, but average performance. Round 10 was an interesting round where players had to make equations using numbers and signs on a ball. I did quite well in this round only to be disappointed later when the round was cancelled due to reasons I would not like to discuss. What a disappointment.
There were a couple of more mistakes in other rounds which ruined the flow of the championship.

28th October
One individual round called 'Screen Test' was supposed to take place with electronic answering machines. It was a huge mess up. Some worked, some seemed to not work, some didn't know whether it worked or no. Result: Back to paper. Waste of time, equipment, etc. It was my first screen test and it opened my eyes. The first few questions, I was too slow and by the time I realised what was happening, it was on Q.10. I put myself together and scored well in the rest of the set. My fault, but I learnt something.
Playoffs got delayed and so did lunch. Team finals were a treat to watch with the USA team racing to victory. However, a Skyscraper Sudoku is more appropriate for a WSC finals.
Individual playoffs were quite disastrous. A wrong puzzle and scrapping of a round is the last thing players want. It seems to be like the first thing that is happening. It also becomes unfair. Mehmet Murat Sevim (Turkey) and Thomas Snyder (USA) had good starts when the round was cancelled. They were unable to make it in the top 4 when the other set was used.
The finals looked more like Ulrich vs Japan rather than a 4-way battle. Three Japanese in top four. Superb performance by team Japan who also took the silver in the team finals. Many would've betted on Ulrich Voigt to add one more to his unmatchable tally and maybe few on Hideaki Jo who was consistently on the top. Ko Okamoto sprang a surprise with his speed in the semi finals and Taro Arimatsu was the cool goer. Surprise surprise! From out of nowhere, Taro Arimatsu cracked all the puzzles in the finals with consistent pace and accuracy to win WPC 2010. Ulrich finished 2nd and Hideaki 3rd.

A short trip and the farewell party wrapped up the event.

Personally, for me WPC 2010 has been a success. I stood 41st and bettered my 2008 rank. I enjoyed the trip and puzzles, though some mistakes could've been avoided.

I'm sure everyone is looking forward for the WPC/WSC combined event in Hungary next year. So am I. Hope it is better and sans errors. Looking forward to Hungary 2011!