use itertools::Itertools;

fn main() {
    let input = advent::read_numbers(17);
    println!("17a: {}", container_fittings(&input, 150));
    println!("17b: {}", minimum_containers(&input, 150));
}

fn container_fittings(input: &[u16], target: u16) -> usize {
    input.iter()
         .powerset()
         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
         .count()
}

fn minimum_containers(input: &[u16], target: u16) -> usize {
    let min_count = input.iter()
                         .powerset()
                         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
                         .map(|containers| containers.len())
                         .min()
                         .unwrap();

    input.iter()
         .powerset()
         .filter(|containers| containers.len() == min_count)
         .filter(|containers| containers.iter().copied().sum::<u16>() == target)
         .count()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test() {
        let input = [20, 15, 10, 5, 5];
        assert_eq!(container_fittings(&input, 25), 4);
        assert_eq!(minimum_containers(&input, 25), 3);
    }
}