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Diffstat (limited to 'day03a/src')
| -rw-r--r-- | day03a/src/main.rs | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/day03a/src/main.rs b/day03a/src/main.rs new file mode 100644 index 0000000..eafb25f --- /dev/null +++ b/day03a/src/main.rs @@ -0,0 +1,105 @@ +/// --- Day 3: Rucksack Reorganization --- +/// +/// One Elf has the important job of loading all of the rucksacks with supplies for the jungle +/// journey. Unfortunately, that Elf didn't quite follow the packing instructions, and so a few +/// items now need to be rearranged. +/// +/// Each rucksack has two large compartments. All items of a given type are meant to go into +/// exactly one of the two compartments. The Elf that did the packing failed to follow this rule +/// for exactly one item type per rucksack. +/// +/// The Elves have made a list of all of the items currently in each rucksack (your puzzle input), +/// but they need your help finding the errors. Every item type is identified by a single lowercase +/// or uppercase letter (that is, a and A refer to different types of items). +/// +/// The list of items for each rucksack is given as characters all on a single line. A given +/// rucksack always has the same number of items in each of its two compartments, so the first half +/// of the characters represent items in the first compartment, while the second half of the +/// characters represent items in the second compartment. +/// +/// For example, suppose you have the following list of contents from six rucksacks: +/// +/// ``` +/// vJrwpWtwJgWrhcsFMMfFFhFp +/// jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL +/// PmmdzqPrVvPwwTWBwg +/// wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn +/// ttgJtRGJQctTZtZT +/// CrZsJsPPZsGzwwsLwLmpwMDw +/// ``` +/// +/// The first rucksack contains the items vJrwpWtwJgWrhcsFMMfFFhFp, which means its first +/// compartment contains the items vJrwpWtwJgWr, while the second compartment contains the +/// items hcsFMMfFFhFp. The only item type that appears in both compartments is lowercase p. +/// The second rucksack's compartments contain jqHRNqRjqzjGDLGL and rsFMfFZSrLrFZsSL. The only +/// item type that appears in both compartments is uppercase L. +/// The third rucksack's compartments contain PmmdzqPrV and vPwwTWBwg; the only common item +/// type is uppercase P. +/// The fourth rucksack's compartments only share item type v. +/// The fifth rucksack's compartments only share item type t. +/// The sixth rucksack's compartments only share item type s. +/// +/// To help prioritize item rearrangement, every item type can be converted to a priority: +/// +/// Lowercase item types a through z have priorities 1 through 26. +/// Uppercase item types A through Z have priorities 27 through 52. +/// +/// In the above example, the priority of the item type that appears in both compartments of each +/// rucksack is 16 (p), 38 (L), 42 (P), 22 (v), 20 (t), and 19 (s); the sum of these is 157. +/// +/// Find the item type that appears in both compartments of each rucksack. What is the sum of the +/// priorities of those item types? +use clap::Parser; + +use std::fs::File; +use std::io::prelude::*; +use std::io::BufReader; +use std::path::PathBuf; + +const FILEPATH: &'static str = "examples/input.txt"; + +#[derive(Parser, Debug)] +#[clap(author, version, about, long_about = None)] +struct Cli { + #[clap(short, long, default_value = FILEPATH)] + file: PathBuf, +} + +fn main() { + let args = Cli::parse(); + + let file = File::open(&args.file).unwrap(); + let reader = BufReader::new(file); + let res = reader + .lines() + .map(|l| l.unwrap()) + .inspect(|l| { + if l.len() % 2 != 0 { + panic!("odd number of items in rucksack") + } + }) + .map(|l| { + let (l, r) = l.split_at(l.len() / 2); + (l.to_owned(), r.to_owned()) + }) + .map(|(lhs, rhs)| { + lhs.chars() + .filter(|l| rhs.contains(*l)) + .map(|l| { + let b = l as u8; + if b > b'a' { + (b - b'a') as u16 + 1 + } else { + (b - b'A') as u16 + 27 + } + }) + .next() + .unwrap() + }) + .sum::<u16>(); + + println!( + "The sum of the priorities of the item that appear in both compartments of each rucksack is {}", + res + ); +} |