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motris
At midnight, I'm officially launching my professional publishing career. In 2013, I will be doing all my puzzle posting at my new Grandmaster Puzzles blog. Many thanks to Dave Millar of The Griddle and Perplexible for help creating the site.

This livejournal will remain as my personal blog site, and will regain some of the character it has lost in recent years. It will still have some reviews of puzzle hunts and competitions, comments on life and sports, and so on. I might even make bold political statements, like "some Americans worry that allowing gays to marry will weaken traditional marriages; I think the real threat to such families will come from cheap, readily accessible (prenatal) genetic testing that will shed light on character flaws far removed from any discussion of sexuality."

But there will no longer be any weekly puzzles here. Please add or relink to my rss feed (http://www.gmpuzzles.com/blog/feed/) if you want to see my now (almost) daily puzzles.

So this, the first puzzle at the new site, will also be the last puzzle here: a Countdown to 2013 Sudoku.



Rules: Place a single digit from 1 to 9 into each cell so that no digit repeats in any row, column, or region.
 
 
motris
28 December 2012 @ 12:05 am
After over 3 years, this will be my last "Friday Puzzle". But this will not be the last puzzle I post online. I'll be launching a new site in January 2013; watch this space for news soon.

As we end 2012, I'm reminded of my top fan list from earlier in the year after the Holiday Hunt. A couple weeks ago I had to write and publish a puzzle in ~15 minutes for my #1 fan. You'll see why I did this in time. My top fan asked for an arrow sudoku and so I'll end the year, and the Friday Puzzles on livejournal, with this rush job of a custom puzzle (that actually came out very well if hard!).

Rules:
Place a single digit from 1-9 into each cell so that no digit repeats in any row, column, or bold region. The digits along the path of each arrow must equal the digit in the circled cell; digits can repeat along an arrow provided they do not occur in the same row/column/region.

 
 
motris
In Ask Dr. Sudoku, I share my perspective on puzzles and puzzling. If you would like to pose a question for a future Ask Dr. Sudoku, please post them here or send them to me at motris at yahoo dot com.

I'm frequently asked in interviews to identify when I first solved puzzles/sudoku. The first answer on puzzles is easy. My answer has typically been that when I was rather young (4-6), I was solving puzzles while playing Atari 800 computer games. Eventually I got into Dell magazines with Logic Problems and Cross Sums and then GAMES magazine with Paint by Numbers and Battleship puzzles, the first logic styles I really liked. Sudoku really didn't catch my attention until 2005-6.

But when it comes to my first sudoku, I've always also said that I probably solved a handful of "Number Place" puzzles a very long time ago in some Dell Math Puzzles and Logic Problems issues. This week, while near my childhood magazines, I found what is likely the very first sudoku I solved in late 1992, over 20 years ago. At the time, as I said, I was solving lots of Logic Problems and Cross Sums and this issue shows more activity on those pages. But I gave the 36-given Number Place puzzles one try, and then passed on doing any more. Dell never knew what they might have had....



So I've been solving sudoku since I was a pre-teen and am entering my third decade with the puzzle now. Another discovery going down nostalgia row with old magazines is that I actually solved more word puzzles/crosswords/etc., or at least attempted them, than I remembered as a child. Perhaps having to talk so much about sudoku has had me reinvent a past where I was unable to solve crosswords, but I was doing the "easy" ones at the same age as the "easy" Number Place puzzles.

Just as now, I went through puzzle magazine issues in slightly different ways (from the front, or by styles). Unlike now, I only have ~10-20% completion of any issue. I also found in my teen years, when I first learned of the World Puzzle Championship (WPC) from the annual reports in GAMES, that I was solving logic puzzles in pen. Those were the days. That I did not have a fax machine in the first year I wanted to try out for the WPC, and that I then forgot about the competition for 10 years until late in graduate school, is an accident in history that I still cannot fully explain.
 
 
motris
21 December 2012 @ 12:24 am
That Magic Order was the perfect "variant" Number Placement puzzle for our 24H puzzle competition round was a choice made by Palmer Mebane who organized Team USA's round. And it was a great choice as a puzzle naturally themed around 24 different numbers in a Latin Square grid. Magic Order debuted on the 2012 USPC and got a great preview treatment from Palmer too. This was my first chance to construct a puzzle in this genre, and I've concluded it is more than a one-off type. Maybe a ten-off genre, but some new things are hidden here. (Note: I am posting the original puzzle. For the competition, as our round was testing far too long, an extra clue was added which restored symmetry but compromises the solve somewhat. That 50-point (medium-hard) form is here, if you want it, but the author strongly prefers this version.)

Rules: Enter the digits 1 through 6 once in each row and column so that 24 distinct 6-digit numbers are formed horizontally and vertically—reading forward and backward. Each clue pointing to a number indicates the position of that number when all 24 6-digit numbers are ordered from smallest to largest.



Solution
 
 
motris
18 December 2012 @ 09:06 pm
My sixth book of puzzles is now released (at least online) with Wei-Hwa Huang as first author. It contains just Tight Fit Sudoku. This is the easiest collection of puzzles of all the books I've written/co-written (similar to the first third of The Art of Sudoku), so a great gift for people new to sudoku variants. But it still offers some puzzles of interest to people who liked the first section of Mutant Sudoku and want to see more development of that idea. I challenge any of you to take the top book off this stack of author copies. Click the tightfitsudoku tag below to see other puzzles of this type.

 
 
 
motris
14 December 2012 @ 12:24 am
Somehow a "24" appeared inside the grid in each of my number placement puzzles at the most recent 24H Puzzle Championship. While internal givens are not typical for most Skyscraper puzzles, I loved the outside clues and solving path too much to add a different digit to the outside. So with your focus on the 2's and 4's, I hope you can enjoy this 40 point puzzle (medium-hard).

Rules: Enter a number from 1 to 7 into each cell so that, in each row and column, every number appears exactly once. Each number in the grid represents the height of a building and the clues on the outside of the grid indicate how many buildings can be "seen" when looking from that direction. Taller buildings block the view of smaller buildings. For example, if a row contained the numbers 15342, then two buildings are seen from the left - 1 and 5 - and three buildings from the right - 2, 4, and 5 - with the other buildings blocked by taller buildings in front of them.



Solution
 
 
motris
07 December 2012 @ 12:24 am
I've written some great sudoku in my lifetime. This is not the best sudoku I've ever written, but in my opinion this is the best sudoku themed around "24" that can be written. In a concise and appropriate number of givens, a clear visual theme is presented that also matters in the solving process. It was worth 20 points (easy-medium) at the recent 24H Puzzle Competition. Enjoy!

Rules: Place a single digit from 1 to 9 into each empty cell so that no digit repeats in any row, column, or bold region.



Solution
 
 
motris
30 November 2012 @ 12:24 am
This week's Friday Puzzle is the last in the object placement section of Team USA's 24 Hour Puzzle Championship set. It is a variation of a recent WPC puzzle style, "Black 21", and probably for being too new and perhaps a bit too long or hard (50 points), it is the only puzzle from our round that was not solved during the competition. So maybe you will be the first (besides the test-solvers).

In addition to the competition puzzle, at the top, I had made a much smaller but less clued puzzle as a first attempt. This tested even harder than the one with all the clues given, but has a cleaner theme and some interesting logic I think.

Rules:
Given are the shapes of a 2 and 4. Place three copies of each (one of each in the example), with rotations allowed but not reflection, so that the outside clues indicate the number of shaded cells in the row/column, and the sum of the digits in the row/column, in some order. Placed shapes may not touch each other, even at a point.

Example


Competition puzzle





Unused puzzle




Solutions:
Competition puzzle
Unused puzzle
 
 
motris
23 November 2012 @ 12:24 am
Another of my puzzles from the Team USA 24h Puzzle Championship Round from a couple weeks ago. This one is my quintessential WPC style: Star Battle. This puzzle was also given a score of 20 points, on the easy-medium side as these puzzles go.


Rules:
Place stars into some cells in the grid so that each row, column, and region contains exactly two stars. Stars cannot be placed in adjacent cells, not even diagonally. (The example uses just one star.)

Example:




Solution
 
 
motris
16 November 2012 @ 12:24 am
I've wanted for awhile to write a 24H Puzzle Competition round and simply not had the time to put it all together, particularly with all the other things I am doing. Fortunately Team USA, lead by Palmer Mebane and helped by Wei-Hwa Huang, got one together this year and I contributed 25% of the puzzles. With three different authors and three different perspectives on difficulties, the competition balance of the set was clearly too hard. But the puzzles were in my opinion uniformly great. I'll be posting mine over the next few weeks. Palmer has already posted all of his.

Our 24H round looks a bit like my first Decathlon structure - 8 genres, with 2 classic and 1 less common style/variation. I took on the object placement and number placement genres. Here is my "24" themed Battleship (20 points - between easy and medium)

Rules:
Locate the indicated fleet in the grid. Each segment of a ship occupies a single cell. Ships can be rotated. Ships do not touch each other, even diagonally. Some ship segments, or sea cells without any ship segments, are given in the grid. The numbers on the right and bottom edges of the grid reveal the number of ship segments in that row or column.




Solution