82 lines
1.9 KiB
Rust
82 lines
1.9 KiB
Rust
use std::collections::HashSet;
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use std::str::FromStr;
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use aoc_2022::*;
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type Input = Vec<Backpack>;
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type Output = i32;
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struct Backpack(HashSet<i32>, HashSet<i32>);
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impl FromStr for Backpack {
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type Err = Report;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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let mut left: HashSet<i32> = HashSet::new();
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let mut right: HashSet<i32> = HashSet::new();
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let mid = s.len() / 2;
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for (i, c) in s.chars().enumerate() {
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let s = if i < mid { &mut left } else { &mut right };
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s.insert(
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c as i32
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+ if c.is_ascii_lowercase() {
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1 - 'a' as i32
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} else {
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27 - 'A' as i32
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},
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);
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}
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Ok(Backpack(left, right))
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}
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}
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impl Backpack {
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fn common_items(&self) -> HashSet<i32> {
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let Backpack(left, right) = self;
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left.intersection(right).cloned().collect()
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}
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fn all_items(&self) -> HashSet<i32> {
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let Backpack(left, right) = self;
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left.union(right).cloned().collect()
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}
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}
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fn common_items(backpacks: &[Backpack]) -> HashSet<i32> {
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backpacks
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.iter()
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.skip(1)
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.fold(backpacks[0].all_items(), |u, b| {
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u.intersection(&b.all_items()).cloned().collect()
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})
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}
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struct Day03;
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impl Solution<Input, Output> for Day03 {
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fn parse_input<P: AsRef<Path>>(pathname: P) -> Input {
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file_to_structs(pathname)
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}
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fn part_1(input: &Input) -> Output {
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input
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.iter()
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.map(|b| b.common_items().iter().sum::<i32>())
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.sum()
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}
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fn part_2(input: &Input) -> Output {
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input
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.chunks(3)
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.map(|backpacks| common_items(backpacks).iter().sum::<i32>())
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.sum()
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}
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}
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fn main() -> Result<()> {
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Day03::main()
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}
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test_sample!(day_03, Day03, 157, 70);
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