adventofcode2022/day04/common.rs

// Copyright 2022 Christian Ulrich
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

use std::io;
use std::ops::RangeInclusive;

pub struct Assignments {}

#[derive(Debug)]
pub struct Assignment {
    range1: RangeInclusive<u8>,
    range2: RangeInclusive<u8>,
}

impl Iterator for Assignments {
    type Item = Result<Assignment, &'static str>;

    fn next(&mut self) -> Option<Self::Item> {
        if let Some(line) = io::stdin().lines().next() {
            let line = line.unwrap();
            if line.len() > 0 {
                return Some(Assignment::from_str(&line));
            }
        }
        None
    }
}

impl Assignment {
    pub fn new(range1: RangeInclusive<u8>, range2: RangeInclusive<u8>) -> Self {
        Self {
            range1: range1,
            range2: range2,
        }
    }

    fn parse_range(input: &str) -> Result<RangeInclusive<u8>, &'static str> {
        if let Some((start, end)) = input.split_once('-') {
            if let (Ok(start), Ok(end)) = (start.parse::<u8>(), end.parse::<u8>()) {
                return Ok(start..=end);
            }
        }
        Err("invalid range string")
    }

    pub fn from_str(input: &str) -> Result<Self, &'static str> {
        if let Some((left, right)) = input.split_once(',') {
            return Ok(Assignment::new(
                Self::parse_range(left)?,
                Self::parse_range(right)?,
            ));
        }
        Err("invalid assignment string")
    }

    pub fn has_obsolete_range(&self) -> bool {
        self.range1.contains(self.range2.start()) && self.range1.contains(self.range2.end())
            || self.range2.contains(self.range1.start()) && self.range2.contains(self.range1.end())
    }

    pub fn has_overlapping_ranges(&self) -> bool {
        self.range1.contains(self.range2.start())
            || self.range1.contains(self.range2.end())
            || self.range2.contains(self.range1.start())
            || self.range2.contains(self.range1.end())
    }
}