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author | June McEnroe <june@causal.agency> | 2016-12-10 18:20:17 -0500 |
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committer | June McEnroe <june@causal.agency> | 2020-11-22 00:14:25 -0500 |
commit | 70e6c95a68991f86b3a88d5f36a13c063b73ee7e (patch) | |
tree | 3de47a0864252e79408492985b4c9363427a4ca4 /src/bin/day09.rs | |
parent | Refactor day 9 (diff) | |
download | aoc-70e6c95a68991f86b3a88d5f36a13c063b73ee7e.tar.gz aoc-70e6c95a68991f86b3a88d5f36a13c063b73ee7e.zip |
Day 9 part 2
Diffstat (limited to '')
-rw-r--r-- | src/bin/day09.rs | 68 |
1 files changed, 59 insertions, 9 deletions
diff --git a/src/bin/day09.rs b/src/bin/day09.rs index 0c6ca98..f559b47 100644 --- a/src/bin/day09.rs +++ b/src/bin/day09.rs @@ -3,13 +3,15 @@ use std::io::{self, Read}; enum Chunk<'a> { Literal(&'a str), Repeat(u32, &'a str), + Recursive(u32, Vec<Chunk<'a>>), } impl<'a> Chunk<'a> { fn len(&self) -> usize { match *self { Chunk::Literal(s) => s.len(), - Chunk::Repeat(n, s) => s.len() * n as usize, + Chunk::Repeat(n, s) => n as usize * s.len(), + Chunk::Recursive(n, ref cs) => n as usize * cs.iter().map(Chunk::len).sum::<usize>(), } } @@ -27,6 +29,28 @@ impl<'a> Chunk<'a> { Ok((Chunk::Literal(&s[..paren]), &s[paren..])) } } + + fn parse_v2(s: &'a str) -> Result<(Self, &'a 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 (mut data, rest) = iter.next().ok_or(())?.split_at(len); + + let mut chunks = Vec::new(); + while !data.is_empty() { + let (chunk, data_rest) = Chunk::parse_v2(data)?; + chunks.push(chunk); + data = data_rest; + } + + Ok((Chunk::Recursive(repeat, chunks), rest)) + } else { + let paren = s.find('(').unwrap_or(s.len()); + Ok((Chunk::Literal(&s[..paren]), &s[paren..])) + } + } } struct File<'a> { @@ -49,26 +73,52 @@ impl<'a> File<'a> { Ok(File { chunks: chunks }) } + + fn parse_v2(mut s: &'a str) -> Result<Self, ()> { + let mut chunks = Vec::new(); + + while !s.is_empty() { + let (chunk, rest) = Chunk::parse_v2(s)?; + chunks.push(chunk); + s = rest; + } + + Ok(File { chunks: chunks }) + } } -fn solve(input: &str) -> usize { +fn solve1(input: &str) -> usize { let file = File::parse(input).unwrap(); file.len() } +fn solve2(input: &str) -> usize { + let file = File::parse_v2(input).unwrap(); + file.len() +} + fn main() { let mut input = String::new(); io::stdin().read_to_string(&mut input).unwrap(); - println!("Part 1: {}", solve(&input)); + println!("Part 1: {}", solve1(&input)); + println!("Part 2: {}", solve2(&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")); + assert_eq!(6, solve1("ADVENT")); + assert_eq!(7, solve1("A(1x5)BC")); + assert_eq!(9, solve1("(3x3)XYZ")); + assert_eq!(11, solve1("A(2x2)BCD(2x2)EFG")); + assert_eq!(6, solve1("(6x1)(1x3)A")); + assert_eq!(18, solve1("X(8x2)(3x3)ABCY")); +} + +#[test] +fn part2() { + assert_eq!(9, solve2("(3x3)XYZ")); + assert_eq!(20, solve2("X(8x2)(3x3)ABCY")); + assert_eq!(241920, solve2("(27x12)(20x12)(13x14)(7x10)(1x12)A")); + assert_eq!(445, solve2("(25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN")); } |