use std::cmp::max;
use std::ops::RangeInclusive;

pub fn day17() {
    solve(&(20..=30), &(-10..=-5));
    solve(&(287..=309), &(-76..=-48));
}

fn solve(target_x: &RangeInclusive<isize>, target_y: &RangeInclusive<isize>) {
    let maxes = (0..=*target_x.end()).flat_map(|vx| {
        (*target_y.start()..=100).filter_map(move |vy| count_steps(vx, vy, target_x, target_y))
    });
    dbg!(maxes.clone().max());
    dbg!(maxes.count());
}

fn count_steps(
    mut vx: isize,
    mut vy: isize,
    target_x: &RangeInclusive<isize>,
    target_y: &RangeInclusive<isize>,
) -> Option<isize> {
    let mut x = 0;
    let mut y = 0;
    let mut max_y = 0;
    loop {
        x += vx;
        y += vy;
        vx -= vx.signum();
        vy -= 1;
        max_y = max(max_y, y);
        if target_x.contains(&x) && target_y.contains(&y) {
            return Some(max_y);
        } else if !target_x.contains(&x) && vx == 0 {
            return None;
        } else if !target_y.contains(&y) && y < *target_y.start() {
            return None;
        }
    }
}