From cassido's February 27, 2023 Newsletter

repeated_groups.rs

pub fn repeated_groups(numbers: &[u32]) -> Vec<Vec<u32>> {
    numbers
        .iter()
        .fold::<Vec<Vec<u32>>, _>(vec![], |mut acc, &n| {
            if let Some(last) = acc.last_mut() {
                if last[0] == n {
                    last.push(n);
                } else {
                    acc.push(vec![n]);
                }
            } else {
                acc.push(vec![n]);
            }

            acc
        })
        .into_iter()
        .filter(|v| v.len() > 1)
        .collect()
}

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

    #[test]
    fn test_repeated_groups() {
        assert_eq!(repeated_groups(&[1, 2, 2, 4, 5]), vec![vec![2, 2]]);

        assert_eq!(
            repeated_groups(&[1, 1, 0, 0, 8, 4, 4, 4, 3, 2, 1, 9, 9]),
            vec![vec![1, 1], vec![0, 0], vec![4, 4, 4], vec![9, 9]]
        );
    }
}