Dasher Pay Calculation

You are given a chronological list of order-related events for a single Dasher during one shift. Each event is a tuple (timestamp, orderId, eventType) where eventType is either "accepted" or "fulfilled". An order is considered active from the moment it is accepted until it is fulfilled. While an order is active the Dasher is on the clock and earns pay for every minute elapsed. The pay rate is not fixed: for every minute the Dasher has exactly k active orders they earn k × $0.30. In other words, the Dasher is paid the base rate of $0.30 per minute for every concurrent active order. Your task is to compute the total dollar amount the Dasher should be paid for the entire shift. You may assume that the input is well-formed: every orderId that appears will have exactly one "accepted" event and one "fulfilled" event, the "fulfilled" event always occurs after the corresponding "accepted" event, and events are given in non-decreasing timestamp order.