Solution to Sudoku no 542

Sudoku no 542 (Tough)

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Solution to Sudoku no 541

Sudoku no 541 (Diabolical)

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Solution to Sudoku no 540

This is the point at which Bowman's Bingo is required:

...and this is the solution:

Sudoku no 540 (Solvable Using Bowman's Bingo)

According to Andrew Stuart's grader and solver, you need to use Bowman's Bingo to solve this puzzle:

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Solving Sudoku no 539 (Now Solved) at sudoku9x9.com/smartsolver.php

I was finally able to solve this puzzle (without brute force) at sudoku9x9.com/smartsolver.php Click on the image to enlarge it and bring it into focus if necessary:

Susu Smitzh sent me the following version on LinkedIn:

Solving Sudoku no 539 (Unsolvable) at www.sudoku-solutions.com

I was able to see the solution at www.sudoku-solutions.com:

...but it was worked out by brute force:

Solving Sudoku no 539 (Unsolvable) in Andrew Stuart's Grader and Solver

This is how far Andrew Stuart's grader and solver got when solving this puzzle:

At this point I used the Solution Count as suggested:

Sudoku no 539 (Unsolvable)

I ran my puzzle creation program and it produced the one below, which has a Hodoku score of 5398. This usually equates to a score of between 600 and 800 in Andrew Stuart's grader and solver so I was surprised when it said it was unsolvable:

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Solution to Sudoku no 538

Sudoku no 538 (Diabolical)

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Solution to Sudoku no 537

Sudoku no 537 (Moderate)

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Solution to Sudoku no 536

Sudoku no 536 (Tough)

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Solution to Hidoku no 5

Hidoku no 5 (6 by 6)

I ran my C program to create a 6 by 6 hidoku solution. Then I used Rainhard Findling's Python solver to create a puzzle from this, as described in earlier posts. I keyed it into an online solver here to produce the image you can see below. Since I last used this, I have written to the site's owner, Amit Kuba, to ask his permission to continue using it for this purpose. He agreed and pointed out a couple of useful points.

Firstly, once you have typed in a puzzle and pressed Solve, you can then press Solve again. If the puzzle has a unique solution, the same answer will reappear. If the puzzle has multiple solutions, a different one will be shown.

Secondly, if you enjoy this puzzle, Amit's solver has many more for you to work through.

Here is a reminder of the rules. I arranged the numbers 1 through 36 in ascending order on the grid below before removing some of them at random. Your job is to replace the numbers I have removed. When you have finished, the grid must contain all the numbers 1 through 36 exactly once and cells with consecutive numbers must be joined horizontally, vertically or diagonally:

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Solution to Sudoku no 535

Sudoku no 535 (Diabolical)

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