pub enum LandscapeType {
    Mountain,
    Valley,
    Neither,
}

fn is_mountain(numbers: &[isize], max: (usize, &isize)) -> bool {
    if max.0 > 0 && max.0 < numbers.len() - 1 {
        for (i, n) in numbers[1..max.0].iter().enumerate() {
            if numbers[i] > *n {
                return false;
            }
        }
        for (i, n) in numbers[1 + max.0..numbers.len() - 1].iter().enumerate() {
            if *n > numbers[max.0 + i] {
                return false;
            }
        }

        true
    } else {
        false
    }
}

fn is_valley(numbers: &[isize], min: (usize, &isize)) -> bool {
    if min.0 > 0 && min.0 < numbers.len() - 1 {
        for (i, n) in numbers[1..min.0].iter().enumerate() {
            if numbers[i] < *n {
                return false;
            }
        }
        for (i, n) in numbers[1 + min.0..numbers.len()].iter().enumerate() {
            if *n < numbers[min.0 + i] {
                return false;
            }
        }

        true
    } else {
        false
    }
}

pub fn landscape_type(numbers: &[isize]) -> LandscapeType {
    if numbers.is_empty() {
        return LandscapeType::Neither;
    }

    let mut min = (usize::MAX, &isize::MAX);
    let mut max = (usize::MIN, &isize::MIN);

    for (i, n) in numbers.iter().enumerate() {
        if n < min.1 {
            min = (i, n);
        }
        if n > max.1 {
            max = (i, n);
        }
    }

    if is_mountain(numbers, max) {
        LandscapeType::Mountain
    } else if is_valley(numbers, min) {
        LandscapeType::Valley
    } else {
        LandscapeType::Neither
    }
}