aoc2020 day5

main.rs

use itertools::Itertools;
use std::fs::File;
use std::io::{BufRead, BufReader};

fn map_to_bool_array(s: &str) -> [bool; 10] {
    let mut output = [false; 10];
    for (i, c) in s.chars().enumerate() {
        output[i] = match c {
            'B' | 'R' => true,
            _ => false,
        }
    }
    output
}

fn bool_to_int(b: bool) -> u32 {
    match b {
        true => 1,
        false => 0,
    }
}

fn map_bool_array_to_u32(arr: [bool; 10]) -> u32 {
    arr.iter()
        .rev()
        .enumerate()
        .fold(0, |sum, (i, d)| sum + (bool_to_int(*d) << i))
}

fn part1(data: &[String]) -> u32 {
    let seats: Vec<u32> = data
        .iter()
        .map(|s| map_to_bool_array(s.as_str()))
        .map(map_bool_array_to_u32)
        .collect();

    *seats.iter().max().unwrap()
}

fn part2(data: &[String]) -> u32 {
    let mut seats: Vec<u32> = data
        .iter()
        .map(String::as_str)
        .map(map_to_bool_array)
        .map(map_bool_array_to_u32)
        .collect();
    seats.sort();
    let my_seat = seats
        .iter()
        .tuple_windows()
        .filter(|(x, y)| *y - *x > 1)
        .collect_vec();
    my_seat.first().unwrap().0 + 1
}

fn main() -> anyhow::Result<()> {
    let data: Vec<String> = BufReader::new(File::open("Data.txt")?)
        .lines()
        .map(Result::unwrap)
        .collect();

    println!("Highest ID is {}", part1(&data));
    println!("My id is {}", part2(&data));
    Ok(())
}

#[cfg(test)]
mod tests {
    use crate::map_bool_array_to_u32;

    use super::map_to_bool_array;
    use test_case::test_case;
    #[test_case("BFFFBBFRRR", 567u32;"EXAMPLE 1")]
    #[test_case("FFFBBBFRRR", 119u32;"EXAMPLE 2")]
    #[test_case("BBFFBBFRLL", 820u32;"EXAMPLE 3")]
    fn test_p1(s: &str, expected_id: u32) {
        let seat = map_to_bool_array(s);
        let seat = map_bool_array_to_u32(seat);
        assert_eq!(expected_id, seat);
    }
}