Google Interview Question for SDE1s


Country: United States
Interview Type: Phone Interview




Comment hidden because of low score. Click to expand.
3
of 3 vote

function getMaxFlightsInAir (flightSchedules) {

    let sortedAirEvents =
      flightSchedules.map(schedule => ({date: schedule.departureTime, eventType: 'departure'}))
        .concat(flightSchedules.map(schedule => ({date: schedule.arrivalTime, eventType: 'arrival'})))
        .sort((eventA, eventB) => {
            return eventA.date - eventB.date;
        });

    let maxFlights = 0;
    let currFlights = 0;
    for (i = 0; i < sortedAirEvents.length; i++) {
        currFlights += sortedAirEvents[i].eventType === 'departure'
          ? 1
          : -1;

        maxFlights = currFlights > maxFlights ? currFlights : maxFlights;

        console.log ("current date: " + sortedAirEvents[i].date + " ( " + sortedAirEvents[i].eventType + "),  currFlights = " + currFlights + ",  maxFlights = " + maxFlights);
    }

    return maxFlights;
}

- shakazulu April 16, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

Make two different array one for departure time and another for arrival time. Sort them according to time. iterate through both array simultaneously increase pointer of array having smaller time. whenever increase pointer of departure array increase flight in air count decrease otherwise. during traversal max count achieved is answer.

- Soniya March 08, 2019 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

type Flight struct {
	Depart int
	Arrive int
}
type Event struct {
	Time  int
	Count int
}

func AirborneFlights(flights []*Flight) int {
	// O(n)
	events := make([]*Event, 0, 2*len(flights))
	for _, f := range flights {
		events = append(events, &Event{f.Depart, 1})
		events = append(events, &Event{f.Arrive, -1})
	}
	// O(n*log(n)) - may be optimized with bucket sort to O(n) in the best case
	sort.Slice(events, func(i, j int) bool {
		if events[i].Time == events[j].Time {
			// Landings should come first
			return events[i].Count < events[j].Count
		}
		return events[i].Time < events[j].Time
	})
	// O(n)
	tally := 0
	max := 0
	for i, e := range events {
		tally += e.Count
		if i == 0 || tally > max {
			max = tally
		}
	}
	return max
}

- BW January 04, 2021 | Flag Reply


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