pub fn one(input: String) {
    let count = input
        .lines()
        .map(|line| to_numbers(line))
        .filter(|numbers| is_safe(numbers))
        .count();
    println!("{}", count);
}

pub fn two(input: String) {
    let count = input
        .lines()
        .map(|line| to_numbers(line))
        .filter(|numbers| is_safe_corrected(numbers))
        .count();
    println!("{}", count);
}

fn to_numbers(line: &str) -> Vec<i32> {
    line.split_whitespace()
        .map(|n| n.parse().unwrap()) // All elements are numbers
        .collect::<Vec<i32>>()
}

fn is_safe(numbers: &Vec<i32>) -> bool {
    let first = numbers.first().unwrap();
    let second = numbers.iter().nth(1).unwrap();
    let incr = if second - first > 0 { 1 } else { -1 };
    let mut cur = first;
    for i in numbers.iter().skip(1) {
        if !is_safe_interval(*cur, *i, incr) {
            return false;
        }

        cur = i;
    }

    true
}

fn is_safe_corrected(numbers: &Vec<i32>) -> bool {
    if is_safe(numbers) {
        return true;
    }

    let count = numbers.len();
    for i in 0..count {
        let mut copy = numbers.clone();
        copy.remove(i);
        if is_safe(&copy) {
            return true;
        }
    }

    false
}

fn is_safe_interval(first: i32, second: i32, incr: i32) -> bool {
    let diff = second - first;
    if diff == 0 {
        return false;
    }

    let norm = diff * incr;
    norm > 0 && norm < 4
}