Yin-Yang Variations Contest

A Yin-Yang Variations Contest was held on 26th February, 2011 from 16:00 - 18:00 GMT (21:30 - 23:30 IST).

The goal is to divide the given grid into two continuous areas - black and white. There cannot be 2x2 squares of the same colour. Black and white circles (if any) show the colour of their cell.

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Password is BW02diogen

All puzzles are variants of Black And White. You can solve some practise puzzles.
You can also view some Solving Techniques.

Results

1. Jana Tylova (Czech Republic) - 95
2. Masashi Sakata (Japan) - 90
3. Hideaki Jo (Japan) - 89
4. Ruben Gafencu (Romania) - 69
5. Nikola Zivanovic (Serbia) - 58
6. Bastien Vial-Jaime (France) - 57
7. Yoichi Enta (Japan) - 56
8. Andrey Lemesh (Russia) - 44
8. Kota Morinishi (Japan) - 44
10. Rohan Rao (India) - 42

Best Indians

10. Rohan Rao - 42
16. Rakesh Rai - 28
24. Swaroop Guggilam - 9
24. Tejal Phatak - 9

Complete Results

Yin-Yang or Black And White is one of my favourite puzzles. The puzzles were very well made and it was worth spending 2hrs on these puzzles, even at midnight.

Logic Masters India - February 2011 Puzzle Test

Logic Masters India announces the February Puzzle Test 'Melon's Puzzle Zoo'. It was held on 26th-27th February, 2011.
The author of the puzzles is Palmer Mebane.

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Password is 20LemONS_freAKSHOw11
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The list of puzzles that will appear in the test are:

1. Castle Wall
2. Out Of Sight
3. International Borders
4. Double Back
5. Akari EX
6. Line Nurikabe
7. Liar Slitherlink
8. Nonconsecutive Fillomino
9. Castle Wall - Masyu
10. Yajilin - Akari
11. Nurikabe - Fillomino
12. Double Back - Country Road

Results

1. Psyho (Poland) - 780
2. Nagata Yuta (Japan) - 710
3. Ulrich Voigt (Germany) - 630
4. Nikola Zivanovic (Serbia) - 620
5. Matej Uher (Slovakia) - 615
6. Zoltan Horvath (Hungary) - 590
7. Nils Miehe (Germany) - 585
8. Tarotaro (Japan) - 585
9. William Blatt (USA) - 555
10. Hideaki Jo (Japan) - 555

Best Indians

37. Rakesh Rai - 300
41. Rohan Rao - 270
80. Anurag Sahay - 90
88. Prasanna Seshadri - 55

Complete Results

Entry to the zoo was free but the wild animals in the zoo were ferocious! It was quite a tough set of puzzles, and I had a bad day.
I loved the Yajilin-Akari puzzle!

Solving Black And White: (Opposite Pairs)

This is a very useful technique of solving Black And White puzzle. Take a look at the two images below.

This situation cannot occur anywhere in any Black And White puzzle! Suppose you find such a situation in a 2x2 region. When you try joining the two white circles, one black circle will be blocked from the other in either way. The same works vice-versa.

Take a look at Puzzle No.341

Try solving as much as possible without guessing.


If you do not know this technique, you may place a white circle at R1C2 and then start scratching your head. Using this technique makes this puzzle a level one puzzle :-)


Take a look at the marked 2x2 region. Since the Opposite Pairs situation cannot occur, R3C2 has to be a black circle.


Using the 2x2 constraint, R4C1 is a white circle.


Using the Edge Connection Technique, the entire edge can be made white.


Using the 2x2 constraints, some more circles can be place.


You should be able to complete it using simple logic.

Now when you look back, I'm sure you will realise how easy this puzzle is with the Opposite Pairs Technique :-)

Other Solving Techniques

Puzzle No.341

Puzzle: Black And White
Author: Rohan Rao

PUZZLE NO.341: BLACK AND WHITE


SOLUTION:

Rules of 'Train'

A train starts at Station No.1 and passes through the stations in numerical order. The journey cannot cross or overlap and must visit every cell exactly once.

EXAMPLE:


UNIQUE SOLUTION:

Puzzle No.340

Puzzle: Tapa
Author: Rohan Rao

PUZZLE NO.340: TAPA


SOLUTION:

Puzzle No.339

Puzzle: Tapa
Author: Rohan Rao

PUZZLE NO.339: TAPA


SOLUTION:

Puzzle No.338

Puzzle: Tapa
Author: Rohan Rao

PUZZLE NO.338: TAPA


SOLUTION:

Tapa Variations Contest 6

Tapa Variations Contest 6 was held on 19th-20th February, 2011.
The author of the puzzles are Gulce Ozkutuk and Serkan Yurekli.

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Password is TapaSabSeAchha
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Results

1. Thomas Snyder (USA) - 938 (60:38)
2. Philipp Weiß (Germany) - 938 (66:59)
3. Psyho (Poland) - 938 (72:44)
4. Florian Kirch (Germany) - 938 (72:46)
5. William Blatt (USA) - 917
6. Kota Morinishi (Japan) - 908
7. Nikola Zivanovic (Serbia) - 893
8. Tarotaro (Japan) - 893
9. Bram de Laat (Netherlands) - 872
10. Zoltan Horvath (Hungary) - 856

Best Indians

30. Rohan Rao - 499
51. Amit Sowani - 338
58. Rajesh Kumar - 308
66. Rakesh Rai - 278
96. Anurag Sahay - 161

Complete Results

I was hoping to improve on my TVC5 performance this time. I think I did fairly same as last time. I'm glad some of my ideas have been used as Tapa variants.
Tapa is getting better and better with every contest! Long live Tapa!

Logic Masters India - February 2011 Sudoku Test

Logic Masters India announces the February Sudoku Test 'Double Delight'. It was held on 12th-13th February, 2011.
The author of the puzzles is Rishi Puri.

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

1. Diagonal-Nonconsecutive Sudoku
2. Jigsaw-Antiknight Sudoku
3. Diagonal-Killer Sudoku
4. Jigsaw-Killer Sudoku
5. Antiknight-Killer Sudoku
6. Nonconsecutive-Killer Sudoku
7. Jigsaw-Diagonal Sudoku
8. Disjoint-Antiknight Sudoku
9. Disjoint-Diagonal Sudoku
10. Nonconsecutive-Jigsaw Sudoku
11. Nonconsecutive-Antiknight Sudoku
12. Diagonal-Antiknight Sudoku

Results

1. WaterlooMathie (Canada) - 1035
2. Thomas Snyder (USA) - 1020
3. Jaku111 (Czech Republic) - 1002
4. Nikola Zivanovic (Serbia) - 1000
5. Chen Cen (China) - 935
6. Rohan Rao (India) - 930
7. Michael Ley (Germany) - 924
8. Takei Daisuke (Japan) - 920
9. Kota Morinishi (Japan) - 904
10. Zafer Huseyin Ergan (Turkey) - 885

Best Indians

6. Rohan Rao - 930
21. Gaurav Korde - 765
24. Jaipal Reddy - 690
33. Harmeet Singh - 575
36. Sumit Bothra - 545

Complete Results

It was a fun test. Applying two constraints to a sudoku required a lot of concentration. In the midst of the test, I kept getting confused between the variants due to repetition. I read 'nonconsecutive' and I applied antiknight! Luckily I caught myself every time I blundered and passed it with a laugh. Its been a while since I stood in the top 10 of an LMI test, so its been a good weekend for me. Congrats to WaterlooMathie for pipping the ever-topping Snyder. Maybe Snyder will be back next month with a vengeance!

Tapa Variations Contest 5

The 2011 Tapa Variations Contest series has begun. This year Logic Masters India will be hosting the competitions. Tapa Variations Contest 5 was held on 5th-6th February, 2011.
The author of the puzzles are Gulce Ozkutuk and Serkan Yurekli.

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Password is 2010MasTeRofTAPANikola

Results

1. Thomas Snyder (USA) - 841 (49:01)
2. Andrey Bogdanov (Russia) - 841 (71:27)
3. Florian Kirch (Germany) - 841 (72:32)
4. Philipp Weiß (Germany) - 812
5. Psyho (Poland) - 777
6. Nikola Zivanovic (Serbia) - 756
7. Michael Ley (Germany) - 741
8. Ulrich Voigt (Germany) - 691
9. Hideaki Jo (Japan) - 689
10. Steven Barge (UK) - 657

Best Indians

28. Rohan Rao - 435
42. Rakesh Rai - 332
62. Anurag Sahay - 242
75. Harmeet Singh - 181
103. Prasanna Seshadri - 61

Complete Results

Beautiful set of puzzles. I wasn't comfortable with Tapa Chess before the test, but I managed to solve it without much trouble. I made some silly error in Tapa Filler. I happily left Math Tapa till the end, one of my least favourite variations. Word Tapa was amazing. It took me a while to figure out the actual usage of the rules, but after that, they solved very nicely. Tapa Rotator was very simple and so was Tapa with Borders. I have never solved Double Tapa in my life (not even the example in the IB) and I surprised myself to the core by solving the Double Tapa puzzle. It was beautiful! And it felt beautiful! Tapa Connection was solvable with a little guesswork, and I just couldn't get through Tapa Possible. Maybe I missed something.
Overall, a superb Tapa variations set and a great start to this year's contests. Looking forward to some more exciting and fun-filled Tapa puzzles in the next few weeks :-)

Tapa Variations Contest 6 will be held on 19th-20th February, 2011.

Sudokucup 5

The 5th Sudokucup was held on 5th-6th February, 2011.
The author of the puzzles are Slovak Sudoku Group K1Z (KLUB 162 Zelenáčov).

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Password is UA8JNNW9!?WPN5

The list of sudokus that appeared in the test are:

1. Classic Sudoku
2. External Sudoku
3. Coloured Sudoku
4. Cross Sudoku
5. Pencilmarks Sudoku
6. Coded Sudoku
7. Domino Sudoku
8. KenKen Sudoku
9. Snake Sudoku
10. Slovak Fence Sudoku
11. Romans Sudoku
12. Surprise Sudoku
13. Symmetric Odd-Even Sudoku
14. Unique Order Sums Sudoku
15. Arrow Sudoku

Results

1. Thomas Snyder (USA) - 300 (01:32)
2. Jan Novotny (Czech Republic) - 300 (01:36)
3. Hideaki Jo (Japan) - 300 (01:45)
4. Florian Kirch (Germany) - 300 (01:46)
5. Yuhei Kusui (Japan) - 300 (01:46)
6. Nikola Zivanovic (Serbia) - 300 (01:50)
7. Jason Zuffranieri (USA) - 300 (01:53)
8. William Blatt (USA) - 300 (01:56)
9. Tiit Vunk (Estonia) - 280 (01:57)
10. Kota Morinishi (Japan) - 280 (01:57)

Best Indians

34. Rohan Rao - 215
43. Rakesh Rai - 193
45. Jaipal Reddy - 191
53. Rishi Puri - 174
80. Tejal Phatak - 142

Complete Results

Nice set of sudokus. I was a little off-colour while solving, so not my best performance. Still managed to beat my other country-mates.
Congrats to Thomas for winning his 2nd Sudokucup in a row.