fn quicksort<T: Ord>(arr: &mut [T]) {
    if arr.len() <= 1 {
        return;
    }
    let pivot = arr.len() / 2;
    let (left, right) = arr.split_at_mut(pivot);
    quicksort(left);
    quicksort(&mut right[1..]);
    let mut temp = Vec::with_capacity(arr.len());
    let (mut i, mut j) = (0, 1);
    while i < left.len() && j < right.len() {
        if left[i] < right[j] {
            temp.push(left[i].clone());
            i += 1;
        } else {
            temp.push(right[j].clone());
            j += 1;
        }
    }
    temp.extend_from_slice(&left[i..]);
    temp.extend_from_slice(&right[j..]);
    arr.clone_from_slice(&temp);
}

fn main() {
    let mut arr = vec![3, 6, 8, 10, 1, 2, 1];
    quicksort(&mut arr);
    println!("{:?}", arr);
}