Solving the GCHQ Christmas Challenge 2022

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Most years, GCHQ (the British intelligence and security organisation) puts out a challenge for puzzlers. This year's, like last, is a Christmas card aimed at schools and colleges - we take you through the puzzles and how to get to the solution.
You can try the challenge here yourself: www.gchq.gov.u...
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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
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Опубликовано:

7 сен 2024

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Комментарии : 88

@zalkin83 Год назад

English is not my native language so I might be wrong here. The way the "Coding" task is written I read that as all blue cells must have the same letter. Wouldn't have taken me as long if it was written as "Replace all the blue cells with letters from PART".

@rixbase Год назад

I was also confused by this. English is my first language.

@bezowee Год назад

For the first time I was quicker than Mark in this language question but only because I'm from Poland 😂

@Wouter10123 Год назад

I don't know Polish, but I happened to know the Russian word сабока, so I was trying to think of an English word that sounded like that, thinking that the Polish word might me similar to the Russian one. Clearly I was wrong, haha.

@bezowee Год назад

@@Wouter10123 Polish and Russian isn't as similar as you think.

@kr12a2y Год назад

Not knowing French or Polish, I thought "if France adds an h to cat, what would Poland add? H is 2 after F, so maybe drog?" After a few minutes I googled France chat and found out what it was and looked for Polish dog.

@KevFrost Год назад

It's worth noting that GCHQ is the modern iteration of codebreakers back from the Bletchley Park days, which famously recruited crossword solvers and maths puzzlers to fight the Nazis.

@Alex_Meadows Год назад

I do like the thought of a group of students collaboratively solving this in an hour, while Mark beasts through it in twenty minutes!

@LordKeram 8 месяцев назад

I think this is where you would make the distinction between wisdom/knowledge and intelligence. Mark's life of experience made him immediately recognize certain patterns which would take minutes if not hours or days to recognize to most others.

@Qazqi Год назад

For that first puzzle, there is some non-meta logic that can be applied to get there too. The flag is unreachable with the gold arrows in their current state, so an odd number of keys must be touched. Flipping the arrows reveals a path straight from the west key to the flag.

@zmaj12321 Год назад

Nice logic

@mccoyn6144 Год назад

I solved it backwards. That seems to be easier.

@leojs5673 Год назад

you being able to solve this so quickly feels like magic, mark!!

@DCRoe Год назад

That was impressive to watch, Mark. I might have solved it but at the very least I would have needed more time and some paper.

@barrytaylor1060 Год назад

I agree with everyone who has made points about the gear ratios. The question does not mention ‘Clicks’ and in the video solution both clicks and turns are used in the explanation. If the first gear wheel rotates 2O-times the top letter arrives at the top so no change. I started by counting teeth passing and driving the second gear ie 20 x 6= 120 teeth which divided by second gear 8-teeth = 15 turns but it doesn’t work for the rest of the gears. I’m an engineer so some experience, particularly liked the Rudolph one though.

@davidrattner9 Год назад

Awesome bonus video Mark!! Great job with it and thank you so much for solving it!!

@jeffreyblack666 Год назад

For that first puzzle, it is much more straight forwards working backwards. The only way to reach the flag is S along the gold arrow or D along a flipped gold arrow. But from the north (to go S) it is unreachable. But from above, you can only reach it by going east along a flipped gold arrow, which you can only reach by going along a flipped gold arrow. And at that point you hit the key and flip everything. The key you can only reach by going west. To get there you can go West, but that location is then only reachable from the flag. The other option is by going up to it. Then you can get there from the flag, or by going east. And then you can reach there by going south from the start. So no need for any thinking about the words. There is no choice. This is the shortest path.

@KestrelQ Год назад

"An odd constraint" - I see what you did there

@grahamrskelly6042 Год назад

That was a great video for the channel, loved it I didn't have to look up pies but I did not know the term cynophile

@leepeel6529 Год назад

I had my students do this, ranging from year 7-13, in groups of 4, and with varying levels of hints. They loved it, and we had a few teams manage to solve it. Great puzzle!

@emilywilliams3237 Год назад

I think you did solve this on the channel last year, and it was fun then and fun today. Thanks for this, and for reminding me of that three words site, which is quite interesting - what a concept! Thank you, Mark.

@adrianhead6272 Год назад

Solved this earlier... seemed easier than last year's (12 minutes for this one)

@longwaytotipperary Год назад

This is fantastic! Thank you, Mark!

@rossylittle16 Год назад

I completed this in 32 minutes and was over the moon with that. Then Mark smashes that time and I realise that I missed so many simple things 😅

@zmaj12321 Год назад

Nice beginner-level puzzles. And very smooth solving!

@zmaj12321 Год назад

Though that gear puzzle is slightly questionable...

@tubasaur Год назад

@@zmaj12321 How so?

@zmaj12321 Год назад

@@tubasaur Chained cogs don't usually rotate at the same rate.

@highpath4776 Год назад

@@zmaj12321 we are not given the gear ratios

@Stormorbiter Год назад

In the engineering section for the 2nd and 3rd cogs, they would complete the same number of rotations, not the same number of “clicks”. This would be 2.5 rotations, leaving the 3rd cog in between the E and F. I guess I can justify this being incorrect by assuming that the chain connecting them it attached to teeth in the same positions as their respective cogs. This would make them move the same number of clicks

@DuncanBooth Год назад

I think the centres where the chain connects are supposed to be sized proportional to the numbers. Certainly the 5 and 7 are different sizes and it may be the same but less obvious with the 8 and 9.

@Alexbrainbox Год назад

Yeah, I got caught up on this too. If we take the numbers to be the radii of the axles then it works though!

@srwapo Год назад

I can't believe I knew something that you didn't! (The Polish word for dog)

@rogermellie001 Год назад

Impressed by your pronunciation of the Polish for dog!

@kr12a2y Год назад

Didn't notice the directions on the seaweed clue, but ended up getting seUweed because I used directions anyhow and figured maybe they say "aup" or something in the UK since seuweed isn't a word.

@mpo87-h1c Год назад

very impressive Mark!

@BLane-xr1ic 5 месяцев назад

There's a new one!!!!! I'm so excited 😂 I have cracked the 13 parts of the picture but not what the letters are!!!

@chrisowen9971 Год назад

Fun! I'm totally going to count this as my first solve on the channel. ;-)

@HienNguyenHMN Год назад

The quick solve in the CODING puzzle is unbelievable.

@th.nd.r Год назад

Really cool puzzle and concept and really wonderful solving. Gosh what3words seems like such a cool thing!!

@MrTechnicolorLover Год назад

I haven't seen anyone else comment, but Mark actually skipped over most of the logic of the "Coding" puzzle. You're supposed to find a new 3-letter word at each *step* - that is, changing only the blue letters would get you 3 brand new 3-letter words, then changing only the greens, etc. Only after the golds do you also get a 9-letter word. Mark just changed all of them at the same time and skipped to the end. He's just too speedy!

@ravtimlady Год назад

Oh, I didn't get that either! I thought you were supposed to do them all at the same time!

@cathybryant5119 Год назад

@@ravtimlady Yeah, the instructions said you should have 3 new 3 letter words that then form a 9 letter word: i.e. CAR, PEN and TRY. Mark did gloss over that pretty quickly.

@Anne_Mahoney Год назад

I noticed that, but recognized that it would come to the same solution in the end. I think it's more elegant with the intermediate steps, though.

@Anne_Mahoney Год назад

Mark, you're right that Greek κύων is cognate with Latin "canis." English "hound," Old Irish "cú" (as in Cú Chullainn), and Sanskrit śvān are also cognates -- they all descend from Proto-Indo-European ḱṷon-. The Polish word isn't related to these, and neither is English "dog."

@craftsmanwoodturner Год назад

Took me over an hour to crack it - I could not work out how to get a word for the first puzzle, and got hung up on "usual" as a not odd word in the sentences. Then my map didn't show Ings as the placename at first, till I zoomed right out. Nice little brain-stretcher, though!

@ravtimlady Год назад

I had the opposite problem: one of the other places shows up as Tony!

@nekogod Год назад

It was a good one this year!

@minion7342 Год назад

love this!

@johncrotty169 Год назад

I thought the answer for Analysis was TWO because it's not odd and you could take the word out and the sentences still make sense!

@tubasaur Год назад

I thought the same. It turned out to not be a valid what3words address though.

@n8style Год назад

With the Analysis puzzle, I thought it would be the word "two" because it's not odd, wish they would've removed that word because imo it makes it ambiguous, the real answer is much nicer though

@xeno7073 Год назад

I got the Rudolph one to the flag but I thought because it was 7 steps the 7 letter word was ‘several’ Damn!

@andrewgrant6516 Год назад

Nicely done

@older-wiser-better Год назад

Holy shit! How fast !

@JigmeDatse Год назад

Is this actually GCHQ? Maybe you answer that as I haven't actually watched the whole thing yet (or even the whole introduction). It *does* seem like it is.

@ifoundthisandthought Год назад

Your videos are great, but this was an easy one. У меня ушло 10 минут, пока я курил. Отличные головоломки.

@techsupportrabbit Год назад

did the mathematics question involve any mathematics ?

@timdiamond1056 Год назад

I was looking for a mathematical solution, rather than just a word game solution. I guessed 'opening' but spent ages trying various number substitutions to resolve it.

@tonymather3973 Год назад

Surely gear ratios make the engineering puzzle incorrect?

@Kradlum Год назад

That's what I am thinking while viewing. Need to spend some time later to look at it in more detail

@AlanJames Год назад

That's that I thought at first, but he has it correct. 1 click on the first cog = 1 click on the second. So we move 20 clicks on the second cog. If it was 20 full turns we had to do then we'd get a different result, but clicks seems correct.

@stevieinselby Год назад

@@AlanJames That's fine where the cogs are meshed, but I don't think it works where the cogs are turned by a chain, unless the axles on each cog are scaled to the right size, which isn't clear.

@blargo Год назад

@@stevieinselby I think that's the intent. It's hard to see with the 8/9 hubs, but the 5/7 pair are clearly scaled.

@AlanJames Год назад

@@blargo and it doesn't work at all if the axles are assumed to be the same size. The third cog ends up between two letters.

@mickeyjupp1 Год назад

No idea what's going on here but it was fun?

@DavidWeinbergUK Год назад

Are GCHQ looking for those that find a solution or those that follow a methodology to arrive at proven answer? Mark guessed in my opinion many steps without solving the challenges. For example, given the maths challenge, I guessed 'opening' with no logic of the hidden number in the word.

@highpath4776 Год назад

Both, I did sit the entrance exams for GCHQ after college, I cannot recall if I passed (I suppose If I had been good I would have been recruited long before the exams !!), I think I failed at a verbal interview.

@milesfinch Год назад

Anyone thinking this is the first time this guy has seen this and is solving it live in the video is in dream land.

@mikechappell5849 Год назад

You obviously haven't seen Mark at work before

@Alex_Meadows Год назад

He's extremely clever, has spent most of his life solving puzzles competitively and is the greatest solver of cryptic crosswords that ever lived.

@milesfinch Год назад

The reason I think he had some "insight" is that he didn't pick the shortest route in Q1, he just went for the word, which in order isn't the shortest route!

@milesfinch Год назад

@@Alex_Meadows I'm in no way questioning his intelligence, the guy is a genius, but sometimes things don't always appear the way they seem.

@tubasaur Год назад

@@milesfinch I solved it as fast as he did in the video, if not faster, and I don't see a shorter route. Besides, the clue gives that it's seven steps.

@roderickdewar1064 Год назад

I suspect Mark already worked it all out in advance before making this video.

@harrymcculla7703 Год назад

Yes, at 17:56 it becomes obvious.

@smrqunofficial Год назад

In no way does this puzzle necessitate Mark working it out ahead of time!

@williammorris7279 Год назад

I think so too, and the reason given by the other responder (i.e. the screenshot at 17.56) does make it fairly clear. Very very unusual for Mark, I think, because he seems so clearly working live in his daily videos. Not complaining, though, as I did enjoy this.

@Alex_Meadows Год назад

@@harrymcculla7703 What happens at 17:56? It shows that he's visited W3W before, but that tells us nothing interesting - if I was going to video myself solving a puzzle that involved an external website, I'd want to make sure that I knew how to use the site before starting the video. On the other hand, I'm quite tickled by the fact that the CtC audience has grown to the point that it's developed its own conspiracy theories.

@harrymcculla7703 Год назад

@@Alex_Meadows it shows more than he just visited w3w, but that he’d previously visited using the relevant keywords. In other words, he had already solved it.