Refactor for Memory Efficiency | Dataford Interview Questions

Your question is Refactor for Memory Efficiency. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

Problem

Gametime United's inventory service loads ticket availability for a single event at a time, but it also caches results so the next lookup for that event is fast. On a big on-sale night with thousands of concurrent events, the service's memory usage climbs until it gets OOM-killed.

func LoadAvailableTickets(eventID string, allTickets []Ticket) []Ticket {
    var available []Ticket
    var eventTickets []Ticket

    for _, t := range allTickets {
        if t.EventID == eventID {
            eventTickets = append(eventTickets, t)
        }
    }

    for _, t := range eventTickets {
        if t.Status == "AVAILABLE" {
            available = append(available, t)
        }
    }

    cache[eventID] = allTickets

    return available
}

Can you refactor this function to improve its memory usage? Explain exactly what's driving the growth and what you'd change.

Your question is Refactor for Memory Efficiency. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

func LoadAvailableTickets(eventID string, allTickets []Ticket) []Ticket {
    var available []Ticket
    var eventTickets []Ticket

    for _, t := range allTickets {
        if t.EventID == eventID {
            eventTickets = append(eventTickets, t)
        }
    }

    for _, t := range eventTickets {
        if t.Status == "AVAILABLE" {
            available = append(available, t)
        }
    }

    cache[eventID] = allTickets

    return available
}

Can you refactor this function to improve its memory usage? Explain exactly what's driving the growth and what you'd change.