# It’s Follow-Up Friday: Hats Off to You edition!

Welcome to Follow-Up Friday!

By this time, you know the drill. Follow-Up Friday is a chance for us to revisit the subjects of previous posts and bring the PuzzleNation audience up to speed on all things puzzly.

And today, I’d like to revisit the subject of brain teasers.

A few years ago, we posted a riddle that had been making the rounds online. It centered around four men buried up to their necks in the ground, each one trying to figure out what color hat he is wearing.

It’s a great exercise in logic and deduction, one that most solvers unraveled after a few minutes.

As it turns out, there’s a more complex version of this riddle. But this one involves 100 people!

One hundred prisoners are lined up single file, facing in the same direction. Each prisoner will be randomly assigned either a red hat or a blue hat.

No one can see the color of his own hat. However, each person is able to see the color of the hat worn by every person in front of him. So the person at the head of the line cannot see the color of anyone’s hat, the second prisoner can see only the first prisoner’s hat, the third can see the first two prisoners’ hats, and so on. The last person in line — the 100th prisoner — can see the colors of the hats on all 99 people in front of him.

Beginning with the last person in line, and then moving to the 99th person, the 98th, etc., each will be asked to name the color of his own hat. If the color is correctly named, the person lives; if incorrectly named, the person is shot dead on the spot.

Everyone in line is able to hear every response as well as hear the gunshot; also, everyone in line is able to remember all that needs to be remembered and is able to compute all that needs to be computed.

Before being lined up and given their hats, the 100 prisoners are allowed to discuss strategy, with an eye toward developing a plan that will allow as many of them as possible to name the correct color of his or her own hat (and thus survive). They know all of the preceding information in this problem. Once lined up, each person is allowed only to say “Red” or “Blue” when his turn arrives, beginning with the last person in line.

What would your plan be to save as many people as possible? How many prisoners can you definitely save?

It’s an absolutely diabolical riddle, one that definitely taxed my puzzle skills. And different plans have different chances for success! Will you save half? 75%? Can you save everyone?

[Click here and scroll down for the solution, courtesy of the folks at IO9.]

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# You’ll never guess this Viking secret message…

I write about codebreaking a lot in this blog. For me, it’s one of the most fascinating real-world applications of puzzle-solving skills. The fact that so many of these stories involve momentous and fascinating times in history — like the Civil War, World War II, and even the identity of the Man in the Iron Mask — is just icing on the cake.

But it’s nice to be reminded that playing around with codes for fun is an equally long-lasting tradition.

K. Jonas Nordby (probably my favorite name that has ever appeared on the blog, by the way), is a runologist — a scholar of runes — at the University of Oslo, and he recently cracked a runic code employed by the Vikings, the jotunvillur code, based on samples scratched into a stick from the 13th century.

From an article on Medievalists.net (though I first spotted the story on IO9):

For the jötunvillur code, one would replace the original runic character with the last sound of the rune name. For example, the rune for ‘f’, pronounced fe, would be turned into an ‘e’, while the rune for ‘k’, pronounced kaun, became ‘n’.

The messages themselves range from simple expressions — “Kiss me” — to taunts by confident codesmiths daring readers to try to crack a given runic code.

Heck, some of the encoded messages even included a Viking cryptographer boasting about his skills!

It’s fun to imagine Vikings toying with various codes and runes during their downtime. Even marauders take time out for some quality puzzling, it seems. =)

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# It’s Follow-Up Friday: Treasure Room edition!

Welcome to Follow-Up Friday!

For those new to PuzzleNation Blog, Follow-Up Friday is a chance for us to revisit the subjects of previous posts and update the PuzzleNation audience on how these projects are doing and what these people have been up to in the meantime.

And today, I’d like to return to the subject of treasure hunts.

A treasure hunt (and its sibling, the scavenger hunt) are terrific puzzle events, because they can combine crafty trivia, questions, and deduction with some good old-fashioned physical activity as you chase down the next clue. (Sometimes, they even involve some digging, if your huntmaster is crafty enough.)

And the parents of one very lucky four-year-old are topnotch huntmasters.

Not only did they organize a treasure hunt for their son, complete with clues to unravel, but the final clue led to his bedroom, instructing him to push aside his dresser.

Behind the dresser, he discovered his birthday gift: a hidden treasure room, all for him!

As it turns out, when the birthday boy was almost two years old, he and his parents moved into a new house. The room intended for him had a small storage room attached, and in a fit of brilliance, his parents not only had the room refurbished, but they kept the room a secret for TWO YEARS before revealing it as his birthday gift for turning four.

Now that is some world-class puzzly skill being put to a wonderful use.

[This story originally appeared on Sarah Goer’s blog Things I Make, and I discovered a repost of the story on IO9.com. All pictures of the treasure room courtesy of Things I Make.]

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# It’s Follow-Up Friday: ABCs and Butterflies edition!

Welcome to Follow-Up Friday!

For those new to PuzzleNation Blog, Follow-Up Friday is a chance for us to revisit the subjects of previous posts and update the PuzzleNation audience on how these projects are doing and what these people have been up to in the meantime.

And today I’d like to talk about patterns.

One of the key puzzly skills a solver should have is an ability to spot patterns. Whether it’s determining a pattern in a series of numbers or spotting irregularities in a pattern that are significant, this level of observation serves puzzlers well in all kinds of solving experiences, from word searches to Match-Up-style art puzzles.

The innate human ability to find patterns in nature has led to numerous scientific discoveries over the years, but it has also led to some wonderful artistic and visual discoveries as well. From shells that adhere to a Fibonacci sequence to patterns in flower petals, patterns (and our ability to uncover them) are everywhere.

Artist and photographer Kjell Bloch Sandved has applied his puzzly attention to detail to photographing moths and butterflies, and he’s developed his own patterns: alphabets hidden in wings.

These patterns come from dozens of different photos, and Sandved has not only created several butterfly alphabets, but he sells custom prints spelling out names and messages in butterfly letters.

Once again, puzzly skills reveal not just brilliance, but beauty in the world as well.

Thanks for visiting PuzzleNation Blog today! You can share your pictures with us on Instagram, friend us on Facebook, check us out on TwitterPinterest, and Tumblr, and be sure to check out our library of PuzzleNation apps and games!

# It’s Follow-Up Friday: Optical Illusion edition!

Welcome to Follow-Up Friday!

For those new to PuzzleNation Blog, Follow-Up Friday is a chance for us to revisit the subjects of previous posts and update the PuzzleNation audience on how these projects are doing and what these people have been up to in the meantime.

And today, I’d like to follow up on the subject of optical illusions with a marvelous new example for you.

I’ve written about optical illusions on several occasions, because they’re wonderful visual puzzles that play with our perceptions in clever, unexpected ways. We either see two images in one, or an object floating in space, or we’re simply misled by careful use of angles and lighting.

The band OK Go released their latest music video this week for the song The Writing’s On the Wall, and the video beautifully utilizes numerous optical illusions to create a mind-bending visual experience.

Check it out:

And this is not the band’s first foray into puzzly music video creation, since they took part in an elaborate Rube Goldberg machine for their song This Too Shall Pass:

Here’s hoping they unleash more puzzle-infused fun in their next video.

Thanks for visiting PuzzleNation Blog today! You can share your pictures with us on Instagram, friend us on Facebook, check us out on TwitterPinterest, and Tumblr, and be sure to check out the growing library of PuzzleNation apps and games!

Today’s a day for sharing the puzzly wealth, so I’ve got a few links for your perusal.

First up is this terrific article from IO9, recommending a number of science-themed apps and games with some seriously crafty puzzle elements to them.

From RNA molecules and gene structures to brainmapping and animal classification, these will fascinate AND inform you all at once. Marvelous stuff.

Next up is a great post by Dan Markowitz on McSweeney’s Internet Tendency, exploring what Rube Goldberg could have created if he was a little more petty and meanspirited. It’s Rude Goldberg Contraptions!

A series of dominoes fall, knocking over a marble that rolls off a ledge, landing on a seesaw that tips downwards, dangling a piece of cheese in front of a gerbil that runs on a hamster wheel, unfurling a roll of toilet paper into a trash can, leaving an empty cardboard tube in the bathroom that you’ll have to replace even though you weren’t the person who used it up.

And finally, a little something for the puzzlers in the audience who like some magic and swashbuckling in their solving. The creative titans behind Dungeons & Dragons are filling the gap between now and the launch of their newest system (D&D Next) by releasing dozens and dozens of out-of-print and retired modules, sourcebooks, and adventures from earlier editions of the game.

You can relive some of your all-time favorite dungeon romps, riddles, and puzzle traps at D&D Classics — they’ve already posted the first edition classic The Temple of Elemental Evil — and any you can’t find there, you can probably track down in downloadable form at DriveThruRPG.