From 85df957431607db45a1f9bf0d4e01e21c676cd2b Mon Sep 17 00:00:00 2001 From: June McEnroe Date: Sat, 17 Dec 2016 00:56:37 -0500 Subject: Day 15 --- src/bin/day15.rs | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 src/bin/day15.rs (limited to 'src') diff --git a/src/bin/day15.rs b/src/bin/day15.rs new file mode 100644 index 0000000..c7006eb --- /dev/null +++ b/src/bin/day15.rs @@ -0,0 +1,91 @@ +use std::io::{self, Read}; + +#[derive(Clone, Copy)] +struct Disc { + positions: u32, + position: u32, +} + +impl Disc { + fn rotate(&mut self) { + self.position = (self.position + 1) % self.positions; + } + + fn is_open(&self) -> bool { + self.position == 0 + } +} + +impl<'a> From<&'a str> for Disc { + fn from(s: &'a str) -> Disc { + let mut iter = s.trim_right_matches('.').split_whitespace(); + Disc { + positions: iter.nth(3).unwrap().parse().unwrap(), + position: iter.last().unwrap().parse().unwrap(), + } + } +} + +#[derive(Clone)] +struct Sculpture { + discs: Vec, + time: u32, + capsule: usize, +} + +impl Sculpture { + fn tick(&mut self) { + self.time += 1; + for disc in &mut self.discs { + disc.rotate() + } + } + + fn drop_capsule(&mut self) -> bool { + while self.capsule < self.discs.len() { + self.tick(); + if self.discs[self.capsule].is_open() { + self.capsule += 1; + } else { + return false; + } + } + true + } +} + +impl<'a> From<&'a str> for Sculpture { + fn from(s: &'a str) -> Sculpture { + Sculpture { + discs: s.lines().map(Disc::from).collect(), + time: 0, + capsule: 0, + } + } +} + +fn solve(input: &str) -> u32 { + let mut sculpture = Sculpture::from(input); + loop { + if sculpture.clone().drop_capsule() { + return sculpture.time; + } + sculpture.tick(); + } +} + +fn main() { + let mut input = String::new(); + io::stdin().read_to_string(&mut input).unwrap(); + + println!("Part 1: {}", solve(&input)); +} + +#[test] +fn part1() { + let input = " +Disc #1 has 5 positions; at time=0, it is at position 4. +Disc #2 has 2 positions; at time=0, it is at position 1. +"; + assert_eq!(5, solve(input.trim())); +} -- cgit 1.4.1