Cartalk Puzzler: Seeing Double 3

[MillerH]

Greetings All,

I listen to the Cartalk Puzzler every week, and occasionally they pose a problem that is solvable programatically.

http://www.cartalk.com/content/puzzler/transcripts/200725/index.html

Give me a word with three, consecutive double letters. I'll give you a couple of words that almost qualify, but don't. For example, the word committee, c-o-m-m-i-t-t-e-e. It would be great except for the i that sneaks in there. Or Mississippi -- M-i-s-s-i-s-s-i-p-p-i. If you could take out those i's it would work. But there is a word that has three consecutive pairs of letters and to the best of my knowledge this may be the only word. Of course there are probably 500 more but I can only think of one. What is the word?

Anyway, I thought that some of y'all might like a quick challenge, and in the mean time you could also learn something! The hardest part to this problem is finding an appropriate dictionary file, so to save you time, I suggest that you could use the 12dicts sourceforge word list:

http://wordlist.sourceforge.net/

- Miller

PS:
If you already have all the appropriate resources, this could easily be solved in less than a minute. It would take 5 if you chose to think about it

 

[travs69]

Bookkeeper

Thank you Encyclopedia Brown !!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It

 

[KevinADC]

one up: subbookkeeper

but I think Miller wanted a programmatical solution, something like:

@_ = qw(Mississippi committee bookkeeper zoo); 
for(@_){
   if (/(\w)\1(\w)\2(\w)\3/) {
      print "$_ = three consecutive pairs\n";
   }
}

------------------------------------------
- Kevin, perl coder unexceptional!

 

[travs69]

Kevin.. for us reg exp beginners will you explain your code?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It

 

[ishnid]

@_ = qw(Mississippi committee bookkeeper zoo);
for(@_){
   if (
        /
        (       # start first capturing group
           \w   # a word character (i.e. a-zA-Z0-9 or _)
        )       # end first capturing group
        \1      # whatever was captured by the first group (i.e. whatever the \w matched)
        (       # start second capturing group
           \w   # a word character 
        )       # end second capturing group
        \2      # whatever was captured by the second group
        (       # start third capturing group
           \w   # a word character
        )       # end third capturing group
        \3      # whatever was captured by the third group
        /x      # the /x allows me to add whitespace and comments above (very handy!)
      ) {
      print "$_ = three consecutive pairs\n";
   }
}

 

[travs69]

I'm not sure where in there you are saying that there are 2 of the same char in a row

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It

 

[KevinADC]

quoted from "Perl 5 by Example":

<QUOTE>
Example: Using the Match Operator

If you need to find repeated characters in a string like the AA in "ABC AA ABC", then do this:

m/(.)\1/;

This pattern uses pattern memory to store a single character. Then a back-reference (\1) is used to repeat the first character. The back-reference is used to reference the pattern memory while still inside the pattern. Anywhere else in the program, use the $1 variable.
</QUOTE>

the same is true for \2 and \3 and etc. You use "\n" (\1, \2, etc) instead of "$n" ($1, $2, etc) while still in the pattern to find a match to the pattern.


------------------------------------------
- Kevin, perl coder unexceptional!

 

[ishnid]

It first matches any character (the first (\w)) then you're checking that that's followed immediately by the same character again (\1 refers to whatever was matched between the previous parenthesis). That's done three times in a row.

 

[travs69]

Ahh.. see how informative we are getting around here. We should have some kind of rating for people to click on just to admit they learned something

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It

 

[travs69]

Oh yeah.. stars for everyone

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It

 

[MillerH]

Well, I'm glad I posted this problem here then. I considered posting it to the "Puzzles for Programmers" section, but honestly I like you guys more.

Glad one of you learned something,
- Miller