Function update_assets 

fn update_assets(
    best_asset: AssetRef,
    capacity: AssetCapacity,
    opt_assets: &mut Vec<AssetRef>,
    remaining_candidate_capacity: &mut HashMap<AssetRef, AssetCapacity>,
    best_assets: &mut Vec<AssetRef>,
)

Update capacity of chosen asset, if needed, and update both asset options and chosen assets