fn closest_numbers(arr: &[i32]) -> Vec<i32> {
    //Time complexity: O(n*log(n))
    //Space complexity (ignoring input): O(n)
    let mut arr = arr.to_vec();
    arr.sort_unstable();

    let mut minimun_value = arr[1] - arr[0];
    let mut pairs = vec![arr[0], arr[1]];
    for index in 2..arr.len() {
        if (arr[index] - arr[index - 1]) == minimun_value {
            pairs.push(arr[index - 1]);
            pairs.push(arr[index]);
        }
        if (arr[index] - arr[index - 1]) < minimun_value {
            minimun_value = arr[index] - arr[index - 1];
            pairs = vec![arr[index - 1], arr[index]];
        }
    }
    pairs
}