adventofcode/2015/day08/problem

Advent of Code

--- Day 8: Matchsticks ---

   Space on the sleigh is limited this year, and so Santa will be bringing his
   list as a digital copy. He needs to know how much space it will take up when
   stored.

   It is common in many programming languages to provide a way to escape
   special characters in strings. For example, C, JavaScript, Perl, Python, and
   even PHP handle special characters in very similar ways.

   However, it is important to realize the difference between the number of
   characters in the code representation of the string literal and the number
   of characters in the in-memory string itself.

   For example:

     • "" is 2 characters of code (the two double quotes), but the string
       contains zero characters.

     • "abc" is 5 characters of code, but 3 characters in the string data.

     • "aaa\"aaa" is 10 characters of code, but the string itself contains six
       "a" characters and a single, escaped quote character, for a total of 7
       characters in the string data.

     • "\x27" is 6 characters of code, but the string itself contains just one
       - an apostrophe ('), escaped using hexadecimal notation.

   Santa's list is a file that contains many double-quoted string literals, one
   on each line. The only escape sequences used are \\ (which represents a
   single backslash), \" (which represents a lone double-quote character), and
   \x plus two hexadecimal characters (which represents a single character with
   that ASCII code).

   Disregarding the whitespace in the file, what is the number of characters of
   code for string literals minus the number of characters in memory for the
   values of the strings in total for the entire file?

   For example, given the four strings above, the total number of characters of
   string code (2 + 5 + 10 + 6 = 23) minus the total number of characters in
   memory for string values (0 + 3 + 7 + 1 = 11) is 23 - 11 = 12.

   Your puzzle answer was 1350.

--- Part Two ---

   Now, let's go the other way. In addition to finding the number of characters
   of code, you should now encode each code representation as a new string and
   find the number of characters of the new encoded representation, including
   the surrounding double quotes.

   For example:

     • "" encodes to "\"\"", an increase from 2 characters to 6.

     • "abc" encodes to "\"abc\"", an increase from 5 characters to 9.

     • "aaa\"aaa" encodes to "\"aaa\\\"aaa\"", an increase from 10 characters
       to 16.

     • "\x27" encodes to "\"\\x27\"", an increase from 6 characters to 11.

   Your task is to find the total number of characters to represent the newly
   encoded strings minus the number of characters of code in each original
   string literal. For example, for the strings above, the total encoded length
   (6 + 9 + 16 + 11 = 42) minus the characters in the original code
   representation (23, just like in the first part of this puzzle) is 42 - 23 =
   19.

   Your puzzle answer was 2085.

   Both parts of this puzzle are complete! They provide two gold stars: **

   At this point, you should return to your advent calendar and try another puzzle.

   If you still want to see it, you can get your puzzle input.

References

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   . https://en.wikipedia.org/wiki/Escape_sequences_in_C
   . https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String
   . http://perldoc.perl.org/perlop.html#Quote-and-Quote-like-Operators
   . https://docs.python.org/2.0/ref/strings.html
   . http://php.net/manual/en/language.types.string.php#language.types.string.syntax.double
   . http://adventofcode.com/
   . http://adventofcode.com/day/8/input