// Маршрут

func getRoute(_ tickets: [[String: String]]) -> [[String: String]] {
    var points = [String: String]()

    for ticket in tickets {
        let from = ticket["from"]!
        let to = ticket["to"]!
        points[from] = to
    }

    let start = Array(Set(points.keys).subtracting(Set(points.values))).first!

    var route = [[String: String]]()
    var currentPoint = start

    while let nextPoint = points[currentPoint] {
        route.append([currentPoint : nextPoint])
        currentPoint = nextPoint
    }

    return route
}

// Пример использования:
let tickets = [
    ["from": "London", "to": "Moscow"],
    ["from": "NY", "to": "London"],
    ["from": "Moscow", "to": "SPb"]
]
let route = getRoute(tickets)
print(route)