You are implementing billing logic for a food-delivery platform. Each completed delivery record contains: - `order_id` - `driver_id` - `requested_at` — when the customer placed the order - `picked_up_at` — when the driver picked up the food - `delivered_at` — when the order was delivered - `distance_km` Use the following rules: **Customer delivery charge** - Base fee: `$2.00` - Distance fee: `$1.20 * distance_km` - Time fee: `$0.25` per minute from `picked_up_at` to `delivered_at` - Peak-hour multiplier: if `requested_at` falls in either `11:00-13:00` or `18:00-20:00`, multiply the total by `1.5` - Return the final value rounded to the nearest cent **Driver payout** - Fixed completion bonus: `$3.00` - Distance payout: `$0.80 * distance_km` - Time payout: `$0.20` per minute from `picked_up_at` to `delivered_at` - A delivery becomes payable at `delivered_at` Implement the following: 1. A function to compute the customer delivery charge for a single order. 2. A function `total_payout_at(timestamp, deliveries)` that returns the total amount owed to all drivers for deliveries with `delivered_at <= timestamp`. 3. Follow-up: explain how you would support a very large number of deliveries and many payout queries at arbitrary timestamps more efficiently than scanning the full list each time.