jonas.tngl.sh
Advent of Code solutions in Rust
feat: day 2 of AoC 2025
+116
-2
+114
aoc_2025/src/day02.rs
+114
aoc_2025/src/day02.rs
···
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use std::ops::RangeInclusive;
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use aoc_companion::prelude::*;
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use itertools::Itertools as _;
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use num_traits::Euclid as _;
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pub(crate) struct Door {
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ranges: Vec<RangeInclusive<u64>>,
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}
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impl<'input> Solution<'input> for Door {
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fn parse(input: &'input str) -> Result<Door> {
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parse_ranges(input).map(|ranges| Door { ranges })
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}
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fn part1(&self) -> u64 {
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self.ranges
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.iter()
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.cloned()
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.flatten()
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.filter(is_simple_invalid_id)
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.sum()
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}
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fn part2(&self) -> u64 {
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self.ranges
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.iter()
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.cloned()
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.flatten()
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.filter(is_invalid_id)
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.sum()
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}
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}
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fn parse_ranges(s: &str) -> Result<Vec<RangeInclusive<u64>>> {
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s.split(',')
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.map(|r| {
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let Some((lhs, rhs)) = r.split_once('-') else {
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anyhow::bail!("missing '-' in range {r:?}");
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};
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Ok(lhs.parse()?..=rhs.parse()?)
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})
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.try_collect()
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}
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fn is_simple_invalid_id(n: &u64) -> bool {
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let s = n.to_string();
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let (mid, 0) = s.len().div_rem_euclid(&2) else {
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return false;
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};
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let (lhs, rhs) = s.split_at(mid);
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lhs == rhs
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}
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fn is_invalid_id(n: &u64) -> bool {
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let s = n.to_string().into_bytes();
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(1..=s.len() / 2)
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.filter(|c| s.len().is_multiple_of(*c))
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.any(|chunk_size| s.chunks(chunk_size).all_equal())
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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const EXAMPLE_INPUT: &str = "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124";
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const EXAMPLE_RANGES: &[RangeInclusive<u64>] = &[
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11..=22,
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95..=115,
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998..=1012,
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1188511880..=1188511890,
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222220..=222224,
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1698522..=1698528,
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446443..=446449,
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38593856..=38593862,
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565653..=565659,
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824824821..=824824827,
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2121212118..=2121212124,
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];
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#[test]
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fn parse_ranges_in_example_input() {
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assert_eq!(parse_ranges(EXAMPLE_INPUT).unwrap(), EXAMPLE_RANGES);
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}
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#[test]
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fn find_simple_invalid_ids_in_ranges() {
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itertools::assert_equal(
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EXAMPLE_RANGES
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.iter()
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.cloned()
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.flatten()
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.filter(is_simple_invalid_id),
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[11, 22, 99, 1010, 1188511885, 222222, 446446, 38593859],
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);
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}
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#[test]
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fn find_all_invalid_ids_in_ranges() {
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itertools::assert_equal(
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EXAMPLE_RANGES
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.iter()
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.cloned()
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.flatten()
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.filter(is_invalid_id),
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[
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11, 22, 99, 111, 999, 1010, 1188511885, 222222, 446446, 38593859, 565656,
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824824824, 2121212121,
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],
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);
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}
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}
+2
-2
aoc_2025/src/main.rs
+2
-2
aoc_2025/src/main.rs
···
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#![allow(refining_impl_trait_internal)]
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mod day01;
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// mod day02;
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mod day02;
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// mod day03;
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// mod day04;
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// mod day05;
···
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async fn main() -> Result<()> {
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aoc_main(&[
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door!(2025-12-01 ~> day01),
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// door!(2025-12-02 ~> day02),
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door!(2025-12-02 ~> day02),
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// door!(2025-12-03 ~> day03),
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// door!(2025-12-04 ~> day04),
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// door!(2025-12-05 ~> day05),