[–] DonaldFisk link

Some years after the faked death of John Darwin, who disappeared after rowing out to sea in his canoe, and was planning to start a new life with his wife in Panama with the insurance payout, the Grauniad had the headline "A man. A plan. A canoe. Panama" in an article (https://www.theguardian.com/uk/2008/jul/23/canoe.ukcrime1) about the case.

reply

[–] AndrewOMartin link

He could have at least had the good decency to have used a KayaK.

reply

[–] thorin link

Pretty sure it was a kayak. People in the UK are very confused by the difference. E.g. British Canoe Union largely supports kayaking. I tend to use the terms interchangeably having been an active kayaker for around 25 years. The British public really struggle with the difference.

reply

[–] AndrewOMartin link

"A man, a plan, a canoe, pasta, heros, rajahs, a coloratura, maps, snipe, percale, macaroni, a gag, a banana bag, a tan, a tag, a banana bag again (or a camel), a crepe, pins, Spam, a rut, a Rolo, cash, a jar, sore hats, a peon, a canal-- Panama!" - Guy Steele, CLTL2

reply

[–] sp332 link
[–] asimjalis link

See banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, banana, bees.

For any N "See [banana,]* bees." can be longer than N.

reply

[–] xamuel link

Think of it like an ad slogan.

"A man, a plan, a canal-- [you should book a trip to] Panama[, a country whose history is summed up by this witty list of things]!"

What I'd like to see is a version where instead of optimizing just for length, the palindrome is optimized for noun-phrases that genuinely have legit connections to Panama (as the brilliant original, "a plan, a man, a canal", does).

reply

[–] marzell link

Apologies, I was actually referring to the very large (6MB!) palindrome text file [0] provided if you follow the article link to the GitHub project [1]. I guess the palindrome of discussion in this link is somewhat ambiguous, because there's not one specific palindrome that the article refers to.

[0] https://raw.githubusercontent.com/rmeertens/palindromes/mast... [1] https://github.com/rmeertens/palindromes

reply

[–] xamuel link

It's the same thing. "A man, a plan, (6MB worth of other junk)-- Panama!"

It's questionable what that other junk has to do with Panama. But grammatically, the structure is the same.

reply

[–] undefined link
[deleted]

reply

[–] marzell link

How does this count as a palindrome? It's just a bunch of nonsense words (ignoring all the acronyms, are the rest all actually even really words?) separated by commas, that doesn't even seem to pretend to take on the structure of a sentence.

Am I misunderstanding the level of coherence of the text? If the requirements are that loose, it seems it would be trivial to generate a 'palindrome' of arbitrary length.

reply

[–] luizfzs link

It's not obvious for me (maybe you are joking and I didn't get it)

reply

[–] kiliankoe link

Try substituting other symbols, which makes it easier to see. 1 for ( and 0 for ) for example.

Then we have

    1010
and

    1001

reply

[–] luizfzs link

mindblow

reply

[–] sombremesa link

It depends on your definition of palindrome. Is it 'reads the same forwards or backwards' or is it 'had the same characters in the second half as in the first, but in reverse order'?

You'll find that according to most dictionaries, ()() is the palindrome here.

Unless you're a robot.

reply

[–] abababba link

Try replacing ( with a and ) with b : abab -> not palindrome abba -> palindrome

reply

[–] kiliankoe link

For a second I thought you have the most fitting username ever for this discussion, but then I saw that your account has just been created :D

reply

[–] onemoresoop link

or substitute the parans to a and b

()() --> abab

())( --> abba

)(() --> baab

We coders could get fooled by this question if we dont pay much attention

reply

[–] kiliankoe link

I was recently dumbfounded by the fact that

    ()() 
is not a palindrome, but

    ())(
is. It's obvious, sure, but it still doesn't look right.

reply

[–] DonaldFisk link

The longest palindrome has infinite length. Start with any palindrome, e.g. "radar". You can make a new palindrome: "radar, sides reversed, is radar". That can then be used to create the palindrome "radar, sides reversed, is radar, sides reversed, is radar, sides reversed, is radar".

You can repeat this indefinitely.

reply

[–] techbio link

"Never odd or even" is one some here might like to see, and perhaps suggests the shorter palindrome, "NaN".

reply

[–] chipuni link

World's shortest palindrome:

reply

[–] interfixus link

Or YYYY-MM-DD as a few of us obsessive smallendians keep insisting.

reply

[–] lazycouchpotato link

Heh, they'd just be the reverse of DD-MM-YYYY :)

But yes, YYYY-MM-DD all the way. It's indispensable to me when sorting file names by date.

reply

[–] lazycouchpotato link

There's a link which takes you to the list of palindrome dates mentioned on the website [1]. There's 38 of them, but they all take the MM/DD/YYYY format into consideration. I wonder how much of a difference it would be by taking DD/MM/YYYY instead.

[1] https://www.livescience.com/33583-palindrome-dates-21st-cent...

reply

[–] fnayr link

Different word trivia that I find fascinating that I feel HNers will also appreciate:

(twelve plus one) is an anagram of (eleven plus two)

I guess that should be called a mathagram?

reply

[–] SippinLean link

I was a fan of this palindromic short story (also in honor of the year 2002): http://spinelessbooks.com/2002/palindrome/

reply

[–] nathell link

Here's a handcrafted one in Polish, 33K+ characters: http://www.palindromy.pl/pal_naj.php

reply

[–] type_enthusiast link

I have to point out Weird Al's "Bob": https://www.youtube.com/watch?v=JUQDzj6R3p4

It's not a palindrome, but is a semi-sensical song masterfully composed entirely out of palindromes (which also does a great job poking fun at Bob Dylan).

reply

[–] nathell link

I'm also reminded of this IOCCC entry: https://www.ioccc.org/1987/westley/westley.c. Strictly speaking, it's not composed of palindromes because of the mirror-image brackets and slashes, but still, impressive.

reply

[–] jacquesm link

This one is a valid sentence in Dutch:

"Nelli plaatst op n parterretrap n pot staalpillen."

The 'n's are a bit of an issue though, 'n in dutch means 'een', but reversed that doesn't work so the 'e's got dropped and replaced by "'" but they move from one side of the n's to the other in the reversal.

reply

[–] alexthehurst link

Did you require a certain time complexity? I came across this on Leetcode. I found it really trivial to implement the “test all substrings” algorithm, but fiendishly difficult to implement the “expand around centers” algorithm.

reply

[–] fjsolwmv link

That's why trick puzzle questions are bad interview questions. Some people have read the centers algorithm

reply

[–] User23 link

It’s not a trick question. It’s just writing a loop any CS graduate or equivalent autodidact should have absolutely no problem with.

We didn’t require any specific time or space complexity. If the candidate whipped out a suboptimal solution quickly and correctly and time permitted we might ask them about that though and how it might be improved. The purpose of the question is not to see if the candidate has memorized the answer or sees a trick, it’s so they can demonstrate basic proficiency and systematic reasoning.

reply

[–] User23 link

We used find the longest palindrome in a string as an interview question at Amazon back in 2004

reply

[–] psalminen link

Thank you. Don't know why I'm being downvoted for asking.

reply

[–] 68c12c16 link

perhaps someone took it too literal and thought, htaed fo guh != hug of death

I upvoted your comment to make it up for you...hope you have a good one...

reply

[–] undefined link
[deleted]

reply

[–] psalminen link

Hug of death?

reply

[–] fjsolwmv link

Perec also wrote a book with no letter E, a mystery about the missing letter. The English translation is called _A Void_. It's hard to make sense in parts, largely works.

At parts it discusses the mysterious missing letter (E is not know) like threeve, the integer between 3 and 4.

reply

[–] etiennemarcel link
[–] luizfzs link

8102018 is not a palindromic because it isn't a valid format date (it is, but is nonsense, so not valid on my standards :).

examples of valid date formats are: yyyy-mm-dd dd-mm-yyyy

reply

[–] evilolive link

engage le jeu que je le gagne

reply

[–] nathell link

And Finnish has saippuakivikauppias.

reply

[–] Aardwolf link

For single words, in Dutch there is:

koortsmeetsysteemstrook

reply

[–] hcs link

So many dynamos

reply

[–] elwell link

Go hang a salami, I'm a lasagna hog.

reply

[–] LearnerHerzog link

I thought the point of palindromes were that they

1: Are the same forwards and backwards

2: Make coherent sense

Still pretty cool nonetheless, I suppose

reply

[–] imtringued link

This palindrome is surprisingly disappointing. Almost every word appears 100s of times...

reply

[–] quickthrower2 link

My two go to palindromes are Mr Merasemordnilapotogowtym!

reply

[–] lowercased link

My 2 "go to" palindromes...

I know a fat man called Ella C Namtafawnoki.

I got hang of fog nah togi.

reply

[–] quickthrower2 link

Whats with Sadick? (15 times!). Also the F*, C and S words!

reply

[–] mkstowegnv link

For a line level palindrome homage to Douglas Hofstadter's Crab Canon see

https://juliagalef.com/2017/02/21/a-poem-for-douglas-hofstad...

reply

[–] ehonda link

wo nemo toss a lasso to me now!

reply

[–] quickthrower2 link

Ada

reply

[–] Aardwolf link
[–] gebeeson link

Yo banana boy

Racecar

reply

[–] white-flame link

Rotavator

reply