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Show HN: A curated list of great puzzles

59 points by sharkdp 11y ago

corbinpage 11y ago
Awesome list. I have a couple I'll add as well.
kej 11y ago
A small suggestion: instead of just puzzle.md and solution.md, it'd be nice to have hint.md or even hint1.md, hint2.md, and so on. Right now your options are either solve it completely yourself or have the answer given to you, and providing various levels of hints help people get some of the enjoyment of solving it even if they don't have that initial eureka moment.
- sharkdp 11y ago
  I like this idea. For some of the puzzles I can certainly come up with some hints which are helpful and not too revealing. Thank you for the feedback!
- deleted 11y ago
  [deleted]
sharkdp 11y ago
In short, the idea behind this list is the following: Puzzle solving is great fun, but often it is really hard to tell if it is worth to invest time into a particular puzzle (without seeing the solution). For the puzzles on the list, I definitely think it was worth to invest some time thinking about them. I hope you will enjoy them as much as I did.
- wesd 11y ago
  I'm not sure if I understand the Rational pirates puzzle or it might need clarification. Specifically "the oldest pirate alive will propose how the coins will be distributed among the pirates,......" "Otherwise, the pirate proposing the scheme will be thrown overboard". I read this as the pirate who proposed the breakdown (the oldest remaining pirate), but in your solution, it sounds like the person who voted against it thrown out.
  - sharkdp 11y ago
    No, you read that correctly in the puzzle description. The oldest pirate will be thrown overboard. My solution was written in a slightly misleading way. I just updated it. I hope it is clear now. Thanks for your feedback!
orodley 11y ago
My favorite site for these kinds of puzzles is https://www.ocf.berkeley.edu/~wwu/riddles/intro.shtml https://www.ocf.berkeley.edu/~wwu/riddles/intro.shtml
- sharkdp 11y ago
  Thank you for the reference. I have never seen this page. Looks very promising.
krick 11y ago
I've read the first one ("Grouped by Color") and isn't the solution more complicated than it needs to? It seems to me, that essentially the same process could be described by one simple rule: every dwarf should take place directly to the right of the rightmost dawrf with blue hat or to the left of the leftmost dwarf with red hat.
- sharkdp 11y ago
  Indeed, this looks like an easier description. Beware, however, that "directly to the right" could be misunderstood. If the first two are B and R, the third has to go between them... but I still like your rule. Will think about it, Thanks!
  - krick 11y ago
    > first two are B and R, the third has to go between them Yes, exactly, and that is directly to the right of B. I assume that dwarfs can always "fit in" between the others. Actually, the rule "directly to the right of the rightmost blue one" would be enough if not the possibility that the first one can be R and then second one doesn't know where to stand and can take the place to the right wearing blue hat himself, which would fuck up the whole algorithm. Hence "to the left of the leftmost red one" part. And it still a little bothers me that, strictly speaking, separation will never happen, as the last dwarf will stand just on the right place, but will never know himself if he wears red or blue hat (others will know though).
    - sharkdp 11y ago
      > > first two are B and R, the third has to go between them > Yes, exactly, and that is directly to the right of B. I assume that dwarfs can always "fit in" between the others. I'm okay with that, just saying that it could be misunderstood/disliked because some people would probably prefer a scheme which works for actual dwarves instead of pointlike :-) > Actually, the rule "directly to the right of the rightmost blue one" would be enough if not the possibility that the first one can be R and then second one doesn't know where to stand and can take the place to the right wearing blue hat himself, which would fuck up the whole algorithm. Hence "to the left of the leftmost red one" part. Yes... or if the first k ones are all red. > And it still a little bothers me that, strictly speaking, separation will never happen, as the last dwarf will stand just on the right place, but will never know himself if he wears red or blue hat (others will know though). True, but from a observer perspective, they definitely managed to order themselves into groups.
tgb 11y ago
A pretty good list you might find things from: http://wiki.xkcd.com/irc/Puzzles http://wiki.xkcd.com/irc/Puzzles
- sharkdp 11y ago
  Yes, "Ants on a meter stick" is from this page - it's a really good collection. I should add a list of resources. Thanks!

59 points by sharkdp 11y ago

Awesome list. I have a couple I'll add as well.

kej 11y ago

A small suggestion: instead of just puzzle.md and solution.md, it'd be nice to have hint.md or even hint1.md, hint2.md, and so on. Right now your options are either solve it completely yourself or have the answer given to you, and providing various levels of hints help people get some of the enjoyment of solving it even if they don't have that initial eureka moment.

sharkdp 11y ago
I like this idea. For some of the puzzles I can certainly come up with some hints which are helpful and not too revealing. Thank you for the feedback!
deleted 11y ago
[deleted]

sharkdp 11y ago

In short, the idea behind this list is the following: Puzzle solving is great fun, but often it is really hard to tell if it is worth to invest time into a particular puzzle (without seeing the solution). For the puzzles on the list, I definitely think it was worth to invest some time thinking about them. I hope you will enjoy them as much as I did.

wesd 11y ago
I'm not sure if I understand the Rational pirates puzzle or it might need clarification. Specifically "the oldest pirate alive will propose how the coins will be distributed among the pirates,......" "Otherwise, the pirate proposing the scheme will be thrown overboard". I read this as the pirate who proposed the breakdown (the oldest remaining pirate), but in your solution, it sounds like the person who voted against it thrown out.
- sharkdp 11y ago
  No, you read that correctly in the puzzle description. The oldest pirate will be thrown overboard. My solution was written in a slightly misleading way. I just updated it. I hope it is clear now. Thanks for your feedback!

orodley 11y ago

My favorite site for these kinds of puzzles is https://www.ocf.berkeley.edu/~wwu/riddles/intro.shtml https://www.ocf.berkeley.edu/~wwu/riddles/intro.shtml

sharkdp 11y ago
Thank you for the reference. I have never seen this page. Looks very promising.

krick 11y ago

I've read the first one ("Grouped by Color") and isn't the solution more complicated than it needs to? It seems to me, that essentially the same process could be described by one simple rule: every dwarf should take place directly to the right of the rightmost dawrf with blue hat or to the left of the leftmost dwarf with red hat.

sharkdp 11y ago
Indeed, this looks like an easier description. Beware, however, that "directly to the right" could be misunderstood. If the first two are B and R, the third has to go between them... but I still like your rule. Will think about it, Thanks!
- krick 11y ago
  > first two are B and R, the third has to go between them Yes, exactly, and that is directly to the right of B. I assume that dwarfs can always "fit in" between the others. Actually, the rule "directly to the right of the rightmost blue one" would be enough if not the possibility that the first one can be R and then second one doesn't know where to stand and can take the place to the right wearing blue hat himself, which would fuck up the whole algorithm. Hence "to the left of the leftmost red one" part. And it still a little bothers me that, strictly speaking, separation will never happen, as the last dwarf will stand just on the right place, but will never know himself if he wears red or blue hat (others will know though).
  - sharkdp 11y ago
    > > first two are B and R, the third has to go between them > Yes, exactly, and that is directly to the right of B. I assume that dwarfs can always "fit in" between the others. I'm okay with that, just saying that it could be misunderstood/disliked because some people would probably prefer a scheme which works for actual dwarves instead of pointlike :-) > Actually, the rule "directly to the right of the rightmost blue one" would be enough if not the possibility that the first one can be R and then second one doesn't know where to stand and can take the place to the right wearing blue hat himself, which would fuck up the whole algorithm. Hence "to the left of the leftmost red one" part. Yes... or if the first k ones are all red. > And it still a little bothers me that, strictly speaking, separation will never happen, as the last dwarf will stand just on the right place, but will never know himself if he wears red or blue hat (others will know though). True, but from a observer perspective, they definitely managed to order themselves into groups.

tgb 11y ago

A pretty good list you might find things from: http://wiki.xkcd.com/irc/Puzzles http://wiki.xkcd.com/irc/Puzzles

sharkdp 11y ago
Yes, "Ants on a meter stick" is from this page - it's a really good collection. I should add a list of resources. Thanks!