AdventOfCode/2015/08/8.md

## \-\-- 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](https://en.wikipedia.org/wiki/Escape_sequences_in_C),
[JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String),
[Perl](http://perldoc.perl.org/perlop.html#Quote-and-Quote-like-Operators),
[Python](https://docs.python.org/2.0/ref/strings.html), and even
[PHP](http://php.net/manual/en/language.types.string.php#language.types.string.syntax.double)
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 `1342`.

## \-\-- Part Two \-\-- {#part2}

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 `2074`.

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

At this point, you should [return to your Advent calendar](/2015) and
try another puzzle.

If you still want to see it, you can [get your puzzle
input](8/input).