Flashback #8 – Killer Sudoku

Round two of the competition included six basic variants with the arranged givens centered on the letters DS – which was the initial of the high school. One of the puzzle I was responsible was the Killer Sudoku. Again, the level should be suitable for attracting new solvers.

Killer Sudoku: Fill in numbers 1-9 so that no number repeats in any row, column or 3×3 outlined regions. The sum of all numbers in a region is given. Numbers may not repeat in a region.

Nonthaburi, August 2011

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Flashback #7 – Quadruple Sudoku

I try to include sudokus every time I write a puzzle set. I don’t like how the fame of sudoku means it often get excluded in “puzzles” in general. My first project consisting of just sudokus came a couple of months after Puzzle Cruise. A staff of a local high school was hosting a sudoku contest hoping to include some variants that programs from the internet couldn’t spew out.

Tackling the job of writing variants were myself and sinchai4547, the current top 2 sudoku solvers in the nation. For a country that has never seen much beyond classic sudoku, we had to be modest with the level of difficulty.

The tournament featured 5 preliminary rounds and the top 20 moves on. After rounds 6 and 7 the remaining top 5 advance to the finals. Here is one puzzle from round 7:

Quadruple Sudoku: Enter digits 1-9 in each row, column and outlined 3×3 boxes. The groups of 4 numbers indicate the contents of that particular 4 boxes.

Example

Nonthaburi, August 2011

Flashback #6 – The Giant Octopus

There is a question whether visual puzzles are puzzles at all. Let alone fun, many people find it more of an eye test. I love visual puzzles. Ask a non-puzzler what his/her first solved puzzle was and it would probably be a word search or a spot the difference.

I’d like to think I’m a good drawer but when my medium is the computer I might as well be using Microsoft Paint. And that’s what I did. I was going to make a reflection spot the differences that commonly crop up in USPC. But I changed my mind when the idea of a co-ordinate pair-finding picture game (also common in USPC) came to mind. Unlike the USPC, this puzzle is one big picture and not a grid of repeating 2-3 small pictures that you can systemically dig out the three pairs.

The Giant Octopus: Find three pairs of identical cells in the following picture. Cells may have been rotated but never reflected.

UKPA, July 2011

During post discussion, this puzzle cost Nikola Zivanovic first place. I believed he had around 30 minutes to find the three pairs but could not find the last pair. Ulrich Voigt finished all puzzles with 30 seconds left on the clock to take first place.

Flashback #5 – Pentomino Pool

The main difference between Puzzle Cruise and USPC was that Puzzle Cruise was themed. 16 out of the 20 puzzles were (very) loosely based on nautical themes. In general, the not-so-themable puzzles were “themed” by giving them new names; Arrow Snake became Loch Ness Monster, Square Route became Lifesavers, Scrabble became Aquarium Display and so on.

One of the few puzzles that weren’t slapped with a new name was this Pentomino Pool. I first encountered this type in the 2009 24HPC set by Zrinka Kokot and Rudi Mrazovic. Their Pentomino Pool was a lot harder than the one I made. Nevertheless, with only 16 correct entries, this was the least solved puzzle on Puzzle Cruise.

Pentomino Pool: Place the 12 pentominoes in the grid so that no pieces touch each other, not even diagonally. All remaining cells are used for paths that connect a number outside the grid to a fish. The number represents the length of that path or the amount of cells occupied by pentominoes for that row/column. The example uses 3 tetrominoes.

UKPA, July 2011