fn closestNumbers(arr: &[i32]) -> Vec<i32> {
    let mut arr = Vec::from(arr);
    arr.sort();

    let mut pairs: Vec<(i32, i32)> = arr
        .windows(2)
        .map(|window| (window[0], window[1]))
        .collect();

    pairs.sort_by(|a, b| (a.1 - a.0).cmp(&(b.1 - b.0)));

    let closest_pair = pairs[0];

    pairs
        .iter()
        .take_while(|pair| pair.1 - pair.0 == closest_pair.1 - closest_pair.0)
        .flat_map(|pair| [pair.0, pair.1])
        .collect()
}