Lo-fi

fn main() {
    let values: Vec<u64> = vec![9, 7, 6, 3, 4, 0, 1, 7, 3, 9];

    let (_, groups): (Option<u64>, Vec<Vec<u64>>) = values
        .into_iter()
        .filter(|value| *value > 0)
        .fold((None, vec![]), |(previous, mut groups), current| {
            match previous {
                Some(previous) if previous >= current => {
                    if let Some(last_group) = groups.last_mut() {
                        last_group.push(current);
                    } else {
                        groups.push(vec![current]);
                    }
                }
                _ => groups.push(vec![current]),
            };
            (Some(current), groups)
        });

    dbg!(&groups);

    let sums: Vec<u64> = groups
        .into_iter()
        .map(|group| group.into_iter().sum())
        .collect();

    dbg!(&sums);
}