73 lines
1.6 KiB
Rust
73 lines
1.6 KiB
Rust
#![warn(clippy::all, clippy::pedantic)]
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use itertools::Itertools;
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use nom::{
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bytes::complete::tag,
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character::complete,
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multi::separated_list1,
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sequence::{pair, preceded},
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IResult,
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};
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/// part6 of day 1 of AOC 2023
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///
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/// # Arguments
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/// - input the puszzle input
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///
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/// # Panics
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/// panics whenever the input isn't parsable
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#[must_use]
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pub fn part1(input: &str) -> String {
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let (_, races) = parse_input(input).expect("input expected");
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races
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.iter()
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.map(|(time, distance)| {
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(0..=*time)
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.filter_map(|x| {
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if (time - x) * x > *distance {
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Some(())
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} else {
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None
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}
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})
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.count()
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})
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.product::<usize>()
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.to_string()
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}
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fn parse_input(input: &str) -> IResult<&str, Vec<(u64, u64)>> {
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let (input, time) = preceded(
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pair(tag("Time:"), complete::space1),
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separated_list1(complete::space1, complete::u64),
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)(input)?;
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let (input, _) = complete::line_ending(input)?;
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let (input, distance) = preceded(
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pair(tag("Distance:"), complete::space1),
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separated_list1(complete::space1, complete::u64),
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)(input)?;
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Ok((
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input,
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time.iter()
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.interleave(distance.iter())
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.copied()
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.tuples()
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.collect(),
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))
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}
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#[cfg(test)]
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mod test {
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use super::*;
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const INPUT: &str = "Time: 7 15 30
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Distance: 9 40 200";
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#[test]
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fn part1_works() {
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let result = part1(INPUT);
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assert_eq!(result, "288".to_string());
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}
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}
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