class Person
{
    public Person( )
    {
        this( "unknown person", -1 );
    }

    public Person( String n, int a )
    {
        name = n;
        age = a;
    }

    public String getName( )
    {
        return name;
    }

    public int getAge( )
    {
        return age;
    }

    public String toString( )
    {
        return getName( ) + " " + getAge( );
    }

    private String name;
    private int age;
}

class Student extends Person
{
    public Student( )
    {
        super( );
        gpa = 0.0;
    }

    public Student( String n, int a, double g )
    {
        super( n, a );
        gpa = g;
    }

    public double getGPA( )
    {
        return gpa;
    }

    public String toString( )
    {
        return getName( ) + " " + getAge( ) + " " + getGPA( );
    }

    private double gpa;
}

public class Day11
{
    public static Person getOlder( Person p1, Person p2 )
    {
        if( p1.getAge( ) > p2.getAge( ) )
            return p1;
        else
            return p2;
    }


    // Assume arr.length >= 1
    public static Person getOldest( Person [ ] arr )
    {
        int maxIndex = 0;

        for( int i = 1; i < arr.length; i++ )
            if( arr[ i ].getAge( ) > arr[ maxIndex ].getAge( ) )
                maxIndex = i;

        return arr[ maxIndex ];
    }

    // Not all entries are Students
    // Option #1: Illegal... IllegalArgumentException
    // Option #2: Include only Students
    public static Person getMaxGPA( Person [ ] arr )
    {
        double maxGPA = -1.0;
        Student max = null;

        for( Person p : arr )
        {
            if( p instanceof Student )
            {
                Student s = (Student) p;
                if( s.getGPA( ) > maxGPA )
                {
                    max = s;
                    maxGPA = s.getGPA( );
                }
            }
        }

        return max;
    }

    public static void main( String [ ] args )
    {
        Person p1 = new Person( "Chris", 29 );
        Person p2 = new Person( "Fran", 40 );

        System.out.println( p1 );
        System.out.println( p2 );

        System.out.println( "Older of p1, p2: " + getOlder( p1, p2 ) );

        Student s1 = new Student( "Billie", 36, 3.8 );
        Student s2 = new Student( "Jackie", 42, 3.6 );

        System.out.println( s1 );
        System.out.println( s2 );
        System.out.println( "Older of s1, s2: " + getOlder( s1, s2 ) );
        System.out.println( "Older of p1, s1: " + getOlder( p1, s1 ) );


        Person [ ] arr = { p1, p2, s1, s2, new Person( "Alex", 30 ) };

        System.out.println( "Oldest of arr: " + getOldest( arr ) );
        System.out.println( "Max GPA: " + getMaxGPA( arr ) );
    }

}