Exam Solutions

public Map<String, Set<String>> favoriteStudySpots
                                (Map<String, Map<String, Double>> ratings, double target) {
    Map<String, Set<String>> result = new TreeMap<>();
    for (String person : ratings.keySet()) {
        result.add(person, new TreeSet<>());

        Map<String, Double> ratingsFor = ratings.get(person);
        for (String locn : ratingsFor.keySet()) {
            if (ratingsFor.get(locn) >= target) {
                result.get(person).add(locn);
            }
        }
    }
    return result;
}

public class GroomingAppointment implements Appointment {
    private Map<String, Integer> services;
    private int month;
    private int day;
    private int hour;
    private int minute;
    private String customerName;

    public GroomingAppointment(String name, int month, int day, int hour, int minute) {
        if (month < 1 || month > 12
            || day < 1 || day > 31
            || hour < 1 || hour > 24
            || minute < 0 || min > 59) {
            throw new IllegalArgumentException();
        }
        services = new HashMap<>();
        this.month = month;
        this.day = day;
        this.hour = hour;
        this.minute = minute
    }

    public void addService(String service, int mins) {
        services.put(service, mins);
    }

    public int totalAppointmentTime() {
        int total = 0;
        for (String service : services.keySet()) {
                total += services.get(service);
        }
        return total;
    }

    public String getDate() {
        return this.month + "/" + this.day;
    }

    public String getTime() {
        return this.hour + ":" + this.minutes;
    }

    public Set<String> getServices() {
        return services.keySet();
    }

    public String toString() {
        return this.name + "'s appointment scheduled for "
                + this.getDate() + " at " + this.getTime();
    }

    public boolean conflictsWith(Appointment other) {
        String otherDate = other.getDate();
        String otherTime = other.getTime();
        return otherDate.equals(this.getDate()) && otherTime.equals(this.getTime());
    }
}

public static void expand(Stack<Integer> s1, Stack<Integer> s2) {
    if (s1.size() != s2.size()) {
        throw new IllegalArgumentException();
    }

    Queue<Integer> q = new LinkedList<Integer>();
    // merge the values into the q
    while (!s1.isEmpty()) {
        q.add(s2.pop());
        q.add(s1.pop());
    }
    // split the values up and make duplicates as you go
    // Variant: You could instead move one set of values back to the Q and then
    // the Q and them move from Q->S later
    while (!q.isEmpty()) {
        int n2 = q.remove();
        int n1 = q.remove();

        for (int i = 0; i < n2; i++) {
            s1.push(n1);
        }
        s2.push(n2);
    }

    // fix order
    s2q(s2, q);
    q2s(q, s2);
    s2q(s1, q);
    q2s(q, s1);
}