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|
use nom::{
bytes::complete::tag,
character::complete::{line_ending, u32 as nom_u32},
combinator::map,
multi::separated_list1,
sequence::tuple,
IResult,
};
use std::{fs, iter::Iterator, ops::RangeInclusive};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("inputs/day_4.txt")?;
let assignments = Assignments::parser(&input).unwrap().1;
dbg!(assignments.count_containing_assignments());
dbg!(assignments.count_overlapping_assignments());
Ok(())
}
#[derive(Debug, PartialEq, Eq, Clone)]
struct Assignments(Vec<AssignmentPair>);
#[derive(Debug, PartialEq, Eq, Clone)]
struct AssignmentPair {
elf_1: Assignment,
elf_2: Assignment,
}
#[derive(Debug, PartialEq, Eq, Clone)]
struct Assignment(RangeInclusive<u32>);
impl Assignments {
fn parser(input: &str) -> IResult<&str, Assignments> {
map(
separated_list1(line_ending, AssignmentPair::parser),
Assignments,
)(input)
}
fn count_containing_assignments(&self) -> usize {
self.0
.iter()
.filter(|pair| pair.one_completely_overlaps_other())
.count()
}
fn count_overlapping_assignments(&self) -> usize {
self.0
.iter()
.filter(|pair| pair.one_overlaps_other())
.count()
}
}
impl AssignmentPair {
fn parser(input: &str) -> IResult<&str, AssignmentPair> {
map(
tuple((Assignment::parser, tag(","), Assignment::parser)),
|(elf_1, _, elf_2)| AssignmentPair { elf_1, elf_2 },
)(input)
}
fn one_completely_overlaps_other(&self) -> bool {
self.elf_1.contains(&self.elf_2) || self.elf_2.contains(&self.elf_1)
}
fn one_overlaps_other(&self) -> bool {
self.elf_1.overlaps(&self.elf_2)
}
}
impl Assignment {
fn parser(input: &str) -> IResult<&str, Assignment> {
map(tuple((nom_u32, tag("-"), nom_u32)), |(start, _, end)| {
Assignment(RangeInclusive::new(start, end))
})(input)
}
fn contains(&self, other: &Assignment) -> bool {
self.0.contains(other.0.start()) && self.0.contains(other.0.end())
}
fn overlaps(&self, other: &Assignment) -> bool {
self.0.contains(other.0.start())
|| self.0.contains(other.0.end())
|| other.0.contains(self.0.start())
|| other.0.contains(self.0.end())
}
}
|
