#[path = "../lib.rs"]
mod lib;

fn check(a: u32, b: u32, increasing: bool) -> bool {
    return (increasing ^ (a > b)) && (1..=3).contains(&a.abs_diff(b));
}

fn is_safe(report: &Vec<u32>) -> (bool, bool) {
    let mut x = 0;
    x += if report[1] > report[0] { 1 } else { -1 };
    x += if report[2] > report[1] { 1 } else { -1 };
    x += if report[3] > report[2] { 1 } else { -1 };
    let inc = x > 0;

    let n = report.len();
    let mut i = 1;
    let mut dampened = false;

    while i < n {
        if check(report[i - 1], report[i], inc) {
            i += 1;
        } else if dampened {
            return (false, false);
        } else if i + 1 == n || check(report[i - 1], report[i + 1], inc) {
            dampened = true;
            i += 2;
        } else if i == 1 || check(report[i - 2], report[i], inc) {
            dampened = true;
            i += 1;
        } else {
            return (false, false);
        }
    }

    return (!dampened, true);
}

fn main() {
    let mut count1 = 0;
    let mut count2 = 0;

    for line in lib::iter_input() {
        let report = line.split(' ').map(|s| s.parse::<u32>().unwrap()).collect();
        let (safe, safe_dampened) = is_safe(&report);
        if safe {
            count1 += 1;
        }
        if safe_dampened {
            count2 += 1;
        }
    }

    println!("part1: {}", count1);
    println!("part2: {}", count2);
}