52 lines
2.3 KiB
Markdown
52 lines
2.3 KiB
Markdown
## \-\-- 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`.
|
|
|
|
To begin, [get your puzzle input](8/input).
|
|
|
|
Answer:
|
|
|