From 5f01234b8680472687ab6128a73bd807e774e2ac Mon Sep 17 00:00:00 2001 From: June McEnroe Date: Sat, 10 Dec 2016 17:15:58 -0500 Subject: Day 9 --- src/bin/day09.rs | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 src/bin/day09.rs (limited to 'src') diff --git a/src/bin/day09.rs b/src/bin/day09.rs new file mode 100644 index 0000000..fb3046f --- /dev/null +++ b/src/bin/day09.rs @@ -0,0 +1,87 @@ +use std::io::{self, Read}; +use std::str::FromStr; + +struct Chunk { + data: String, + repeat: u32, +} + +impl Chunk { + fn len(&self) -> usize { + self.data.len() * self.repeat as usize + } + + fn parse(s: &str) -> Result<(Self, &str), ()> { + if s.starts_with('(') { + let mut iter = s[1..].splitn(3, |ch| ch == 'x' || ch == ')'); + + let len = iter.next().ok_or(())?.parse().map_err(|_| ())?; + let repeat = iter.next().ok_or(())?.parse().map_err(|_| ())?; + let (data, rest) = iter.next().ok_or(())?.split_at(len); + + let chunk = Chunk { + data: data.to_owned(), + repeat: repeat, + }; + + Ok((chunk, rest)) + } else { + let paren = s.find('(').unwrap_or(s.len()); + + let chunk = Chunk { + data: s[..paren].to_owned(), + repeat: 1, + }; + let rest = &s[paren..]; + + Ok((chunk, rest)) + } + } +} + +struct File { + chunks: Vec, +} + +impl File { + fn len(&self) -> usize { + self.chunks.iter().map(Chunk::len).sum() + } +} + +impl FromStr for File { + type Err = (); + fn from_str(mut s: &str) -> Result { + let mut chunks = Vec::new(); + + while !s.is_empty() { + let (chunk, rest) = Chunk::parse(s)?; + chunks.push(chunk); + s = rest; + } + + Ok(File { chunks: chunks }) + } +} + +fn solve(input: &str) -> usize { + let file: File = input.parse().unwrap(); + file.len() +} + +fn main() { + let mut input = String::new(); + io::stdin().read_to_string(&mut input).unwrap(); + + println!("Part 1: {}", solve(&input)); +} + +#[test] +fn part1() { + assert_eq!(6, solve("ADVENT")); + assert_eq!(7, solve("A(1x5)BC")); + assert_eq!(9, solve("(3x3)XYZ")); + assert_eq!(11, solve("A(2x2)BCD(2x2)EFG")); + assert_eq!(6, solve("(6x1)(1x3)A")); + assert_eq!(18, solve("X(8x2)(3x3)ABCY")); +} -- cgit 1.4.1