Sudoku 88: Untouch Sudoku

 

Rules: Classic sudoku rules apply. Additionally, identical digits do not touch each other diagonally.

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Solution

Sudoku 87: Thermo Sudoku

 

Rules: Classic Sudoku rules apply. Additionally the digits in the thermometer shapes must be strictly increasing in each cell from the round bulb to the flat end.

Links: 

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Solution

Sudoku 86: Fraction Sudoku

Similar to last post, sharing a sudoku which I had created for practice for WSC for the Indian team. This time it is a Fraction Sudoku.

Rules: Put numbers 1/2, 1/3, 2/3, 1/4, 3/4, 1/5, 2/5, 3/5, 4/5 instead of 1-9 so that each number appears exactly once in each row, column and 3x3 outlined box. Letter N means that numbers in neighbouring cells have the same numerator. Letter D means that numbers in neighbouring cells have the same denominator. All possible letters N and D are given.

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Solution

Sudoku 85: Determinant Sudoku

As you might be aware, recently World Sudoku Championship was held at Kraków, Poland. Determinant Sudoku was one of the new variant introduced this year. I had created a Determinant Sudoku for practice for the Indian Team. Hope you like it :)

Rules: Place a digit from 1 to 9 into each empty cell in the grid so that each digit appears exactly once in each row, column and 3x3 outlined box. Additionally, the number in the small square is equal to the determinant of the 2x2 matrix cells and the calculations is "(a*d)-(b*c)". In a matrix: a is the upper left cell, b is upper right cell, c is the bottom left cell and d is the bottom right cell.

Links:

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Solution

Sudoku 84: Outside + Palindrome Sudoku

Rules: Place a digit from 1 to 9 into each empty cell in the grid so that each digit appears exactly once in each row, column and 3x3 outlined box. Each digit outside the grid appears in one of the first three cells of the corresponding direction. In addition, numbers along each grey line must form a palindromic sequence.

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Solution

Indian Sudoku Championship, 2022

I'm happy to share that last weekend I participated and finished at 13th place in the Indian Sudoku Championship (ISC) organised by Logic Masters India.

While this rank is way below my personal best of 7th position at ISC, I'm really happy that I participated after so long.

From 2015 to 2017, I was very regular at sudoku championships and used to participate in online as well as offline events every now and then. However, for the past 4 years I've not been able to remain much active in sudoku due to personal and professional commitments. While I was occupied elsewhere I always wanted to come back to my hobby! And this year I finally did so. I'm happy that I participated in all the online qualifier rounds of ISC and finally at the offline finals.

The next step is definitely to consistently keep participating and improve over the years. And also to make the sudoku blog active again.

It was a wonderful experience participating in the championships and meeting the fellow puzzlers after so long. I would like to thank Logic Masters India, all the organisers, sudoku authors, testers & volunteers for organising such a splendid event. I would also like to congratulate Prasanna Seshadri, Rohan Rao, Kishore Sridharan & Pranav Kamesh for grabbing the top 4 positions.

Below I share the experience of every round of ISC and how it went for me.

With my performance at the online qualifier rounds I started with a base position of 13th rank at the offline finals.

The first round was all Classic Sudokus. 9 sudokus to be solved in 40 minutes. While there are multiple approaches I've used in the past, this time I had decided that in every round I'll start with the middle difficulty sudokus, progress to higher difficulty ones and then come to the easier ones at the end when last few minutes are left. I started the round with the 5th sudoku, was able to solve 5th, 6th & 7th sudoku but broke (made mistake) in the 8th one. I decided to move to the next one instead of fixing it. But again the 9th one was an 80-pointer and I got stuck in it. So, I started solving the 3rd sudoku. I had to make a guess in the 3rd one but finished 3rd & 4th sudoku and later moved to 2nd one. Struggling in the last few seconds I finished 2nd one as well only to realize later that in the last minute hassle I placed an 8 instead of a 9 in the last cell!

The 2nd round had 9 sudokus (1 classic & 8 variants) to be solved in 55 minutes. I started the round with 85-pointer Thermo sudoku, finished it. Then finished Odd Even Sudoku, Battenburg + Killer Sudoku (my personal favourite from the round), Outside Sudoku & Arrow sudoku (yet another fantastic sudoku). In the last few minutes I moved to Classic sudoku. It was a low pointer but somehow I got stuck in it and couldn't complete it. However, I was happy with my performance in this round.

But when the results came out, I found that I had made last cell mistakes in 2 sudokus and lost 145 points because of them. This is one of the most common mistakes which you will find almost all the participants make in at least one sudoku in such championships. But this was a major set back for me as I was down at 18th position now from the 13th position.

The 3rd round had some unfamiliar variants -- 10 of them to be finished in 65 minutes. I could solve 5 of them, was solving the 6th one but couldn't do so within time. Yet again I made a last cell mistake in an 85-pointer sudoku and I was still at 18th position after this round as well. At this point I was gravely disappointed with the mistakes I was making. I had just one round left to rise in ranks.

The final round had 10 sudokus which were connected with each other forming a Pyramid Scheme. I gave my best at the round. I was able to finish the tough ones but got stuck in 25-pointer easy Classic. I took a lot of time to solve it but couldn't move forward as the other sudokus were dependent upon this one. Fortunately I finished 7 out of 10 sudokus in this round and finished at 13th position.

Looking forward to more such championships!

Sudoku 83: Surplus Sudoku

 When sun lies over your head from 1 pm to 6 pm in these summers, have an Orange Stick ice-cream at 7 pm :p

Also, don't forget to solve the sudoku :p

Rules: Place a digit from 1-9 in each empty cell so that each digit appears exactly one in every row & column. In regions with more than 9 cells, some numbers repeat but each number should appear at least once.  

Links:

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Solution

Sudoku 82: Sum Frame Sudoku

 

Rules: Place a digit from 1-9 in each empty cell so that each digit appears exactly one in every row, column and 3x3 outlined box. Additionally the numbers outside represent the sum of first three numbers in corresponding direction.

Links:

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Solution

Sudoku 81: Odd Even Queen Sudoku

 

Rules: Classic Sudoku rules apply. Additionally, exactly two numbers(one odd and one even) behave like chess Queens. Two queens of the same parity cannot be placed along the same row, column or diagonal of any length. The Queens should be determined as a part of solving.

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Solution

Sudoku 80: Sudo-Kurve Sudoku

 

Rules: Place a digit from 1 to 9 in each empty cell so that no digit repeats in any row or bold region. Some rows bend as indicated by following the curved lines.

Links:

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Solution