[HN Gopher] Primel - guess a 5 digit prime number - each guess m...
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       Primel - guess a 5 digit prime number - each guess must be a prime
        
       Author : sebg
       Score  : 125 points
       Date   : 2022-01-21 13:39 UTC (9 hours ago)
        
 (HTM) web link (converged.yt)
 (TXT) w3m dump (converged.yt)
        
       | graycat wrote:
       | Hint: The number should not end in any of 0, 2, 4, 6, or 8!
        
       | paradite wrote:
       | Looks very nice. However it took me a while to figure out why I
       | kept getting error. It wasn't obvious to me that you are required
       | to enter prime numbers only. Maybe consider dropping this
       | constraint?
       | 
       | Also, might want to disable text selection via css because I kept
       | selecting the numbers on the button on my phone.
        
       | basemntunivrse wrote:
       | This is really cool, nice idea!
       | 
       | Also, the following script might help to make the game more
       | accessible (or to help you cheat :P) -                 // note:
       | game doesn't seem to automatically clear at the end, so in the
       | dev console use:       // window.localStorage.clear();       //
       | then refresh the page            const prime = n => {         for
       | (let i = 2, s = Math.sqrt(n); i <= s; i++) {           if (n % i
       | === 0) {             return false;           }         }
       | return n > 1;       }       const generateNums = digits => (
       | m => [...Array(9 * m).keys()].map(i => i + m)
       | )(Math.pow(10, digits - 1));       const generate5DigitPrimes =
       | () => generateNums(5).filter(prime);            const
       | all5DigitPrimes = generate5DigitPrimes();            // updated
       | to take an optional array (defaults to all5DigitPrimes)       //
       | this means you can chain the check function to do things that
       | normal regex can't do       // e.g. check(/some_regex/,
       | check(/some_other_regex/))       const check = (r, a =
       | all5DigitPrimes) => a.filter(p => r.test('' + p));
       | 
       | Usage:
       | 
       | paste the above code into the dev console
       | 
       | type 'all5DigitPrimes' and press Enter to see a list of all
       | 5-digit primes
       | 
       | type 'check(/some_regular_expression/)' to see a filtered list of
       | primes that match your regular expression
        
         | scythe wrote:
         | I also cheated with a script, leading to this:
         | 
         | https://pastebin.com/sQtekXCW
        
       | nickponline wrote:
       | My first inclination was to write a solver :)
       | 
       | https://gist.github.com/nickponline/9a3fb1ee5333c52ed195625e...
        
       | culi wrote:
       | A list of possible primes showing up as you type would be
       | helpful...
        
       | MauranKilom wrote:
       | 12347           -         65393         ++--        [solution
       | next - omitted for spoiler reasons]
       | 
       | I was more surprised about how little trial and error I needed to
       | find primes than about how few guesses it actually took...
        
         | bidirectional wrote:
         | log(100000) is 5, so approximately 1 in 5 numbers below 100k is
         | prime. Obviously those in the range 10000-99999 are less dense,
         | but primes are still surprisingly common.
        
           | madcaptenor wrote:
           | You want a natural log there; ln(100000) ~ 11.5.
           | 
           | That being said, the pool you're really working from is the
           | numbers with last digit 1, 3, 7, or 9. One out of every 4.6
           | such numbers under 10^5 is prime. So just guessing until you
           | find a prime is practical.
        
             | [deleted]
        
             | lupire wrote:
             | And you can knock out multiples of 3 by adding digits.
        
               | madcaptenor wrote:
               | Sure, but that's a little more work than just looking at
               | the last digit, so it's debatable whether it's worth the
               | trouble.
        
             | bidirectional wrote:
             | Ah you're correct. Annoying how Google interprets log(x) as
             | base-10 (but more shame on me for not realising that e^5 is
             | obviously not 100000). In my experience everyone uses log
             | and ln interchangeable outside of lessons at school.
        
               | Eduard wrote:
               | log(x) historically conventionally defaults to base-10.
               | https://en.m.wikipedia.org/wiki/Common_logarithm
        
             | 100721 wrote:
             | Hi, can you provide some search terms that will help me
             | understand the relationship between ln and prime density?
        
               | sebzim4500 wrote:
               | https://en.wikipedia.org/wiki/Prime_number_theorem
        
               | [deleted]
        
               | knuthsat wrote:
               | Or https://en.wikipedia.org/wiki/Prime-counting_function
               | .
        
           | iso1631 wrote:
           | Looks like there's 8,363 5 digit primes, from 10007 to 99991,
           | so about 1 in 11
        
             | jameshart wrote:
             | Why isn't 00002 your lower bound?
        
               | chockablock wrote:
               | The game does not accept leading zeros (00017: "Not a 5
               | digit prime")
        
         | syrgian wrote:
         | Same, I was so surprised to get it solved at the second row,
         | after ~8 attempts to find a prime without the numbers that had
         | not matched.                   12347           -
         | [solved]
        
           | 07d046 wrote:
           | It seems a lot of us came up with 12347 for the first line.
        
             | MauranKilom wrote:
             | While natural in terms of just inputting numbers, it's also
             | not bad to use as first guess because primes are denser (in
             | an "average absolute distance" sense) the lower the
             | magnitude you're around. Without having checked, I would
             | expect there to be more primes of the form 123** than
             | 987**, so you're more likely to gain correct digits with
             | this guess.
             | 
             | Edit: I checked, it's 9 vs 8 primes. But nearby prefixes
             | also have more and there's a lot of variance. Still, there
             | are overall more primes among the same range of smaller
             | numbers (1000-5499 has ~4400 primes, 5500-99999 has ~4000).
             | 
             | Note that, despite this, you probably shouldn't include 0
             | in the starting guess (e.g. 10247) because 0 will be in the
             | solution less frequently (can't be the leading digit),
             | meaning you gain less info on average.
        
             | scythe wrote:
             | 56809 is a pretty good second guess for this situation :p
        
               | dalmo3 wrote:
               | Ha, those were exactly my first 2 guesses.
        
       | egberts1 wrote:
       | MasterMind!
       | 
       | Just say so!
        
       | emeraldd wrote:
       | Ok, so once you've won how do you start a new game?
        
       | phreenet wrote:
       | First attempt I tried:                 45677       56779 (Didn't
       | read the instructions, the 5 should have stayed from 1st)
       | 15809       35869       65839 (Solved)
       | 
       | EDIT: I'm slow today, just realized they are both the same
       | primes.
        
       | wy35 wrote:
       | The repo linked in the game seems to lead to a general Wordle
       | clone. I'm guessing you forked it and replaced the keyboard with
       | numbers and the word checker with a prime number checker?
        
         | pxx wrote:
         | That's a lot more work than just populating with a list of
         | eligible primes
        
       | [deleted]
        
       | [deleted]
        
       | [deleted]
        
       | metalliqaz wrote:
       | So are people just really good with numbers? I don't know any 5
       | digit primes nor do I know a way to calculate them on the fly.
        
         | jerf wrote:
         | If you are on Unix:                   primes 10000 99999 | less
         | 
         | Then recall that "less" includes a regex-based search on the /
         | key.
         | 
         | This doesn't give you direction as to the best to try, of
         | course, but it's hard to beat it in terms of bang for the buck
         | if you're just going to try a few.
        
         | Maursault wrote:
         | You can guess a prime relatively easily given a few attempts,
         | as besides 2 and 5, all other primes will have a 1, 3, 7, or 9
         | as its least significant digit. So, for starters, you'd never
         | guess a number with any other least significant digit.
        
         | tobyjsullivan wrote:
         | I used this site to explore options.
         | http://compoasso.free.fr/primelistweb/page/prime/liste_onlin...
         | It's a bit tedious but still fun-ish and seemed better than
         | guessing.
         | 
         | Unlike Wordle, I assume it's unreasonable to expect a player to
         | know primes so I don't think I'd call this cheating.
        
         | NikolaeVarius wrote:
         | Its a weird thing where in smaller scales, primes numbers that
         | LOOK prime are decent candidates of actually being prime.
        
           | madcaptenor wrote:
           | All one- and two-digit numbers that look prime are prime,
           | except 91.
           | 
           | This assumes that you can easily identify - multiples of 2
           | and 5 (by their last digit) - multiples of 3 (the sum of
           | their digits is divisible by 3) - multiples of 11 (for two-
           | digit ones, they have both digits the same: 11, 22, 33, ...,
           | 99) - squares
           | 
           | So the first number that looks prime but isn't is the product
           | of the two smallest primes that aren't "easy", which is 7*13
           | = 91.
        
         | Mogzol wrote:
         | Yeah I would really rather this just let me guess non-primes
         | even though that would make it more challenging. Trying to find
         | a prime by guessing randomly over and over is pretty
         | frustrating.
        
         | eganist wrote:
         | I intuited a probably-inaccurate trick with exponentially
         | raising a small prime (e.g 7*7*7etc), doubling the multiple
         | (*2), and subtracting 1 (to get an odd number).
         | 
         | That got me two substantially-different primes and narrowed my
         | numbers a lot, which then became guesswork.
         | 
         | My guesses in the end:                 -?---       ?---!
         | ?-??!       ?!??!       !!!!!
        
           | metalliqaz wrote:
           | lol this would not help me at all
           | 
           | by the way am I supposed to take some meaning from the
           | italicized '7' or was that just a typo?
        
             | ColinWright wrote:
             | He probably had 7x7x7, but with asterisks instead of the
             | "x"s.
        
               | eganist wrote:
               | correct, thanks for the heads up. Fixed
        
           | madcaptenor wrote:
           | The number you come up with in that way is at least
           | guaranteed to not be divisible by 2 or 7. Obviously that
           | doesn't mean it's prime but it definitely helps your odds.
        
             | naniwaduni wrote:
             | Also usefully, (2(a+1)^n-1) % a = (2a(a+1)^(n-1) +
             | 2(a+1)^(n-1) - 1) % a = 1. So if you choose one of the 3k+1
             | primes, it's also guaranteed not divisible by 3.
        
         | NeoTar wrote:
         | apparently 9.3% of all '5 digit' numbers are prime, so random
         | guessing isn't a bad strategy - you'll find one in 10.75
         | totally randomly chosen numbers to be prime.
         | 
         | Being a little smarter, prime number can only end in a 1, 3, 7
         | or 9 - (ending in 0, 2, 4, 6, 8 would be even, ending in 5
         | would be odd), so in fact it's more like 25% of 'likely'
         | guesses.
        
           | kadoban wrote:
           | IIRC, randomly guessing is _always_ a good strategy for "give
           | me a prime in the range [a, b]" , in other words that's
           | what's used for algorithms that need primes anyway. Either
           | guess and check or guess and increase-by-2-until-prime.
           | 
           | Does work _much_ better in this range than at crypto sizes
           | though.
        
         | emaro wrote:
         | I thought the same, but it rejects guesses that are not valid
         | prime numbers. So you'll find some with trial and error. With
         | that it took me only three guesses.
        
       | tlholaday wrote:
       | 00003 is not a prime?
        
         | tlholaday wrote:
         | Edit: Alas, the yellow and green square emoji are discarded.
         | 
         | 
         | Partially interpreted:
         | 
         | &#x1F7E8;
         | 
         | &#x1F7E8;&#x1F7E8;
         | 
         | &#x1F7E8;&#x1F7E8;&#x1F7E8;&#x1F7E9;
         | 
         | &#x1F7E9;&#x1F7E9;&#x1F7E9;&#x1F7E9;&#x1F7E9;
        
         | simonlc wrote:
         | It's not a 5 digit prime.
        
           | tlholaday wrote:
           | 0 is a digit.
           | 
           | Apparently I have stumbled over an idiom of the prime-
           | enthusiast community.
        
             | eCa wrote:
             | > 0 is a digit.
             | 
             | It's not a significant digit[0], though, when it's leading.
             | 
             | [0] https://en.wikipedia.org/wiki/Significant_figures
        
             | zamadatix wrote:
             | I don't think the different usage is related to an
             | individual group rather context, particularly when
             | referring to numbers.
             | 
             | E.g. 3 is a 1 digit number because that's the number of
             | digits needed to uniquely identify 3. There are infinitely
             | more ways to identify 3 the number with padded 0s but those
             | aren't useful unless you're talking about
             | combinations/sequences of groups of digits (like random
             | numbers or PIN codes) instead of actual number values.
        
             | [deleted]
        
             | geephroh wrote:
             | I agree -- maybe technically not a digit, but I'd argue
             | it's a UX issue if it is allowed in the leading slot.
             | 
             | But I still love the concept!
        
             | NickM wrote:
             | I don't think it's specific to "the prime-enthusiast
             | community". Most people would look at you oddly if you
             | claimed that 3 is a five-digit number.
        
               | lapetitejort wrote:
               | On the flip side, many people here would claim that
               | 0x00000003 is an eight digit number.
        
               | floatingatoll wrote:
               | Only to win an argument by nitpick golfing. In everyday
               | serious conversation that's a 4-byte number, not an
               | 8-digit number.
        
       | [deleted]
        
       | beardyw wrote:
       | Can't work out how to play again.
        
         | Tempest1981 wrote:
         | This is modeled on Wordle, which only allows one game per
         | day... to keep you coming back. Apparently it is effective.
        
         | mandarax8 wrote:
         | Clear local storage.
        
           | KMnO4 wrote:
           | Wow, that's some bad UX. Especially when it can't as easily
           | be done on mobile.
        
             | SamBam wrote:
             | It's a clone of Wordle. There is a single correct answer
             | per day, and everybody gets the same puzzle. There will be
             | a new answer tomorrow.
             | 
             | So, since the puzzle will be the same, there isn't a huge
             | amount of reason to let you reset.
             | 
             | The page could have made that clearer. (Wordle says it when
             | you open it the first time, and also under the help menu.)
             | I double-checked this by looking at the sourcecode.
        
               | beardyw wrote:
               | > So, since the puzzle will be the same, there isn't a
               | huge amount of reason to let you reset.
               | 
               | Good point! Somehow, being numbers, I thought it would
               | just make up another.
        
             | roelschroeven wrote:
             | Or play in privacy mode.
             | 
             | The intent, I think, is to mimic how Wordle works. Wordle
             | has one puzzle per day, progress and statistics are stored
             | in a cookie on your local machine (and only there). You can
             | clear the cookie or use another browser or privacy mode to
             | play multiple times per day, but you'll always get the same
             | word.
        
             | floatingatoll wrote:
             | It's intentional, same as Wordle's designed did it.
        
           | citizenkeen wrote:
           | That... is not ideal.
        
         | [deleted]
        
       | vehemenz wrote:
       | I solved it on the first try! (after cheating with localStorage)
        
       | sebastialonso wrote:
       | This is neat! Although the prime constraint makes this a lot
       | easier than Mastermind
        
       | arbol wrote:
       | This is way harder than wordle
        
       | zamadatix wrote:
       | 97501 and 24683 will get you all of the numbers (and maybe some
       | position matches), from there it becomes much easier.
        
         | tlholaday wrote:
         | Enable "hard mode" in a future release, which, like Wordle's
         | hard mode, rejects any guesses ruled out by previous answers.
        
       | ryanschneider wrote:
       | Someone more skilled than me make Assemble, each box is an x86
       | opcode and the program must terminate (or maybe NOT terminate?).
        
       | randstring wrote:
       | I couldn't come up with any primes, nor I'm any good with
       | numbers, so I started with the prime from the game example:
       | 
       | 71429
       | 
       | Than I already had one digit guessed and simply clicked the
       | unused numbers from the virtual numpad below and got to having
       | all digits with just two being in the wrong place:
       | 
       | 35869
       | 
       | Now this was easy to figure out.
       | 
       | Got the following score: 20 3/6
        
       | nsxwolf wrote:
       | Primel 20 6/6
        
       | raxxorrax wrote:
       | Not easy. Mine:
       | 
       | 65537
       | 
       | 12497
       | 
       | 80747
       | 
       | 23459
       | 
       | 64217
       | 
       | 14771
        
       | simonlc wrote:
       | Primel 20 2/6
       | 
       | Edit, I guess HN doesn't like emojis lol
        
       | logitjoy wrote:
       | I did 2 _3_ 5 _7_ 11*13 - 1
        
         | logitjoy wrote:
         | Primel 20 6/6
         | 
         | 30029 12347 33331 13337 86539 65839
        
           | [deleted]
        
       | cbsmith wrote:
       | Amusing to see people starting with odd digits so much. You're
       | going to have to use an odd digit in every guess, so you can more
       | efficiently explore the space by going after all the even digits
       | first with 24683.
        
         | mlyle wrote:
         | 56843 was mine, for similar reasons.
        
       | bArray wrote:
       | My path:
       | 
       | 1 2 [3] 4 7
       | 
       | [5][6](8)[9][3]
       | 
       | (6)(5)(8)(3)(9)
       | 
       | Fun game! Might take a while to explain to people though!
        
       | popctrl wrote:
       | This reminds me of something about flash games in the 2000s. I
       | was in high school at the time and every morning in class I would
       | check onemorelevel, kongregate, etc for new games. There was a
       | pattern in flash games where someone would make a great simple
       | game with an interesting, novel, or long-forgotten mechanic. It
       | would get to the frontpage of all these sites, and a few months
       | later you'd see that mechanic mixed with every other popular
       | flash game mechanic. It was really cool to see a community of
       | creative people embrace an idea and then beat it to death in a
       | short period of time. I think in a lot of other creative genres,
       | this kind of "copying your idea but a twist" is seen as poor
       | form, plagiarism, or derivative. Maybe the flash game community
       | was low enough stakes that it welcomed that kind of community
       | engagement. I wonder what the people actually making the games
       | thought.
       | 
       | Anyway, this is a really cool example of that. It's wordle, but
       | with a twist.
        
         | d0mine wrote:
         | "Immature poets imitate; mature poets steal; bad poets deface
         | what they take, and good poets make it into something better,
         | or at least something different. The good poet welds his theft
         | into a whole of feeling which is unique, utterly different than
         | that from which it is torn."
         | https://www.benshoemate.com/2012/08/02/what-does-it-mean-goo...
        
       | omarhaneef wrote:
       | Crowdsourcing decryption on the web is so crazy... it just might
       | work.
       | 
       | Now come up with a hash that starts with many zeroes.
        
         | whoomp12342 wrote:
         | "oops, sorry that one was discovered already"
        
         | throwhauser wrote:
         | There should be an option to use the "numbers" that are prime
         | in a different universe.
        
           | lupire wrote:
           | what would that be?
        
       | tobyjsullivan wrote:
       | My side-project this week has been searching for an optimal
       | Wordle strategy. I figured it would make a great blog post but I
       | haven't got that far yet.
       | 
       | Step 1 is to find an optimal starting word. My most insightful
       | finding so far has came from trying to define a cost function for
       | comparing potential starting words. It turns out that "% of
       | potential guesses [not] eliminated" is an excellent loss
       | function.
       | 
       | Importantly, the full set of all Acceptable Guesses is knowable.
       | For any given (guess, answer) pair, the game provides feedback
       | about each character (or digit). There are basically three pieces
       | of potential feedback: (N)ot Used, (U)sed Elsewhere, (E)xact
       | Match. For example, a single guess might produce the feedback
       | "NUNNE". Each of these will eliminate some subset of Acceptable
       | Guesses which means you can attribute a fixed value between 0.0
       | and 1.0 to any piece of feedback, and multiply those together to
       | get the loss score of a given guess. Average that across all
       | Potential Answers to get a cost score.
       | 
       | Not sure what my goal of this post is. Guess I just wanted to
       | share that these games are as much fun to analyze as they are to
       | play (if not more).
        
         | hadem wrote:
         | My first two guesses are usually AUDIO and RENTS if it helps
         | -\\_(tsu)_/-
        
           | oceliker wrote:
           | I use ADIEU to get 4 wovels, likely the same reason you
           | picked AUDIO.
        
           | Tuna-Fish wrote:
           | SLATE/ROUND/PICKY has been a 8/8 for getting the correct word
           | on the 4th guess since I started using it.
        
         | xtracto wrote:
         | I've given some light thought to this: There are several which
         | are considered "good starting words", that mainly contain lots
         | of vowels or most common used letters (such as "audio", Raise,
         | etc). Then, as a second word, you could use another word that
         | complements those letters (audio/rents, raise/mould ).
         | 
         | But there is a better strategy (similar to what is used in
         | those interview puzzles of "From N weights, find 1 that is
         | different in X measurements of a scale): The fact that you
         | input some vowels and see that they are _not_ in there, tells
         | you that the remaining ones MUST be in the word (treating Y as
         | a vowel as well). So it might be possible to come up with a
         | strategy that uses that negative information as well to
         | minimize the search space.
        
         | rozab wrote:
         | I made a lil clone of wordle and found that the full list of
         | solutions, _past and future_ , is right there in the minified
         | js. Could be useful for your analysis.
         | 
         | Maybe I shouldn't be sharing this, it's a bit sad to break the
         | illusion that the creator is picking a new word for us every
         | day.
        
         | airza wrote:
         | You are looking for Information Gain and Mutual Information
         | (concepts from information theory). Have fun!
        
         | HWR_14 wrote:
         | Since you've been looking into it, how are words with multiple
         | of the same letters treated on Wordle. If there are two (or
         | three) 'E' in the solution or the guess?
        
           | CrazyStat wrote:
           | I've spent some time analyzing Wordle (my starting words are
           | SOARE and then BUILT, unless I've already got strong clues
           | from SOARE).
           | 
           | If the answer has one E and you guess a word with two Es,
           | only one of the Es will be marked correct (green/yellow). If
           | one of the Es is in the correct place, it will be green and
           | the other one grey. Otherwise the first E will be yellow and
           | the second grey. So if the answer has fewer Es than your
           | guess the game tells you.
           | 
           | If the answer has more Es than your guess there is no
           | indication of this.
        
         | bluesign wrote:
         | I think single level is not enough for the best guess. There is
         | a maximum depth ( 6 guesses ). So strategy should consider also
         | this limit.
        
       | [deleted]
        
       | hcrisp wrote:
       | Harder than Wordle but still solvable. Mine:
       | 95317       -+-       25943        +- -       65393       ++--
       | 65839       +++++
       | 
       | Some luck, but you can also lock in odd numbers before proceeding
       | to add evens. And it obviously can't end in an even.
        
       | 07d046 wrote:
       | I thought coming up with primes would be very challenging, but
       | then my first three guesses were all prime (all I did was pick
       | numbers that ended with odd numbers that weren't five). I got it
       | on the fourth after a few attempts at entering the number - the
       | prime constraint here makes it easier.
       | 
       | There are 8,363 five digit primes. If you limit your guesses to
       | numbers ending in 1, 3, 7, and 9, there is a 23% chance of
       | randomly picking a prime.
        
       | airstrike wrote:
       | I got a popup 'Not a 5 digit prime' on my first try and it
       | wouldn't let me try any further. Not sure if I'm dense or if the
       | UX is just terrible
       | 
       | I had tried 18141, by the way, which I modestly think was a
       | pretty good guess in hindsight given its only two factors are 3
       | and 6047. 19141 would have been a prime, but perhaps not the one
       | I was supposed to find? I don't play Wordle so I'm a little
       | confused
        
         | xendo wrote:
         | when sum of the digits is divisible by 3, the number itself is
         | divisible by 3
         | 
         | 1+8+1+4+1 = 15 15/3 = 5
        
           | airstrike wrote:
           | Sure, but that shouldn't halt the game entirely, should it?
        
             | bidirectional wrote:
             | Only primes are valid guesses, just like how in Wordle only
             | English words found in a dictionary are valid.
        
         | NAHWheatCracker wrote:
         | You have to click delete to reset the last digit.
         | 
         | I think it should clear the whole guess after an invalid guess.
        
         | floatingatoll wrote:
         | Were you able to hit the delete key and remove the typed
         | numbers? (Works on wordle too)
        
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       (page generated 2022-01-21 23:01 UTC)