use aoc22::{day15, util};
use itertools::Itertools;

const ROW: isize = 2000000;

pub fn main() {
    let sensors = day15::parse_sensors(&util::parse_input());

    let covered = sensors
        .iter()
        .map(|s| s.covered(ROW))
        .filter(|r| !r.is_empty())
        .sorted_by_key(|r| *r.start());

    let mut max_x = isize::MIN;
    let mut total_covered = 0;
    for range in covered {
        let (min, max) = range.into_inner();
        if min > max_x {
            total_covered += max - min + 1;
        } else if max > max_x {
            total_covered += max - max_x;
        }
        max_x = max_x.max(max);
    }

    let n_beacons = sensors
        .iter()
        .map(|s| s.loc_b)
        .filter(|b| b.0 == ROW)
        .unique()
        .count() as isize;

    println!(
        "Impossible positions in row {}: {}",
        ROW,
        total_covered - n_beacons
    );
}