108 lines
3.1 KiB
Rust
108 lines
3.1 KiB
Rust
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// Copyright 2022 Christian Ulrich
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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use std::collections::BTreeSet;
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use std::io;
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#[derive(Debug, PartialOrd, PartialEq, Eq, Ord, Clone)]
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pub struct Item(u8);
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#[derive(Clone)]
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pub struct Rucksack {
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c1: BTreeSet<Item>,
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c2: BTreeSet<Item>,
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}
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pub struct Rucksacks {}
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pub struct Group {
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rucksacks: Vec<Rucksack>,
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}
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impl Item {
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pub fn new(value: char) -> Result<Self, &'static str> {
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match value {
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'A'..='z' => Ok(Item(value as u8)),
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_ => Err("item value out of range"),
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}
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}
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pub fn priority(&self) -> usize {
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match self.0 as char {
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'a'..='z' => (self.0 - 96).into(),
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'A'..='Z' => (self.0 - 38).into(),
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_ => panic!("not reachable"),
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}
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}
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}
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impl Rucksack {
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pub fn new(compartment1: &str, compartment2: &str) -> Result<Self, &'static str> {
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let collection1: Result<BTreeSet<_>, _> = compartment1.chars().map(Item::new).collect();
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let collection2: Result<BTreeSet<_>, _> = compartment2.chars().map(Item::new).collect();
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Ok(Rucksack {
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c1: collection1?,
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c2: collection2?,
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})
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}
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pub fn items(&self) -> BTreeSet<Item> {
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self.c1.union(&self.c2).cloned().collect()
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}
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pub fn duplicates(&self) -> Vec<Item> {
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self.c1.intersection(&self.c2).cloned().collect()
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}
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}
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impl Iterator for Rucksacks {
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type Item = Result<Rucksack, &'static str>;
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fn next(&mut self) -> Option<Self::Item> {
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if let Some(line) = io::stdin().lines().next() {
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let line = line.unwrap();
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if line.len() > 0 {
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if line.len() % 2 == 0 {
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let (c1, c2) = line.split_at(line.len() / 2);
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return Some(Rucksack::new(c1, c2));
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}
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return Some(Err("input file contains invalid line"));
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}
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}
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None
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}
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}
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impl Group {
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pub fn new(rucksacks: &[Rucksack]) -> Self {
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Self {
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rucksacks: rucksacks.into(),
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}
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}
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pub fn badge(&self) -> Result<Item, &'static str> {
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if let Some(first) = self.rucksacks.first() {
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let mut items = first.items();
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for next_items in self.rucksacks[1..].iter().map(Rucksack::items) {
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items = items.intersection(&next_items).cloned().collect();
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}
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if items.len() == 1 {
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return Ok(items.iter().next().cloned().unwrap());
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}
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}
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Err("cannot determine badge")
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}
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}
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