pub fn minimum_abs_difference(mut arr: Vec<i32>) -> Vec<Vec<i32>> {

let mut diff_map = HashMap::new();

let mut min_diff = i32::MAX;

arr.sort();

for i in 0..arr.len()-1 {

let d = arr[i+1] - arr[i];

if d < min_diff { min_diff = d; }

diff_map.entry(d).or_insert(vec![]).push(vec![arr[i], arr[i+1]]);

}

match diff_map.get(&min_diff) {

Some(v) => v.clone(),

None => vec![]

}

}