Find Active Time

/*
You are given a series of inputs representing delivery events. Each event is represented by an array of length 3:
[1, 1591846068, 0]

    The first element is an order number
    The second is the timestamp
    The third is either 0 (representing a pickup) or 1 (representing a dropoff)

Given a series of events, return the total active time, calculated by the period of time where they have an active delivery (if they've dropped everything off, they are not considered active until they pick something up again).


Add one restriction at a time and have the candidate have their code test for that condition.

Examples
Input:
[1, 1591846068, 0]
[2, 1591846070, 0]
[1, 1591846071, 1]
[2, 1591846080, 1]
[3, 1591846090, 0]
[3, 1591846102, 1]
Output: 24

Function Signature
func activeDeliveryTime(events: [Int]) -> Int
*/