[파워 유저를 위한 파이썬express] 12장 프로그래밍 programming 솔루션 답지

1. 
class Point(object):
    def __init__(self,x,y):
        self.x=x
        self.y=y
    def __str__(self) :
       return "(%d, %d)" % (self.x, self.y)

class Point3D(Point):
    def __init__(self,x,y,z):
        super().__init__(x, y)
        self.z=z
    def __str__(self) :
       return "(%d, %d, %d)" % (self.x, self.y, self.z)

my_point=Point3D(1,2,3)
print(my_point)

3.
import cmath  # complex math 모듈 
class Function:
    def __init__(self):
        pass
    def value(self, x):
        pass

class Quadratic(Function):
    def __init__(self, a, b, c):
        self.a=a
        self.b=b
        self.c=c

    def value(self, x):
        return (self.a)*x**2+(self.b)*x+(self.c)
        
    def get_roots(self):
        d = (self.b**2) - (4*self.a*self.c)

        sol1 = (-self.b-cmath.sqrt(d))/(2*self.a)
        sol2 = (-self.b+cmath.sqrt(d))/(2*self.a)

        print(f'solution: {sol1}, {sol2}')

e = Quadratic(1, 5, 6)
e.get_roots()

5.
class Animal:
    def __init__(self, age):
        self.age=age

    def eat(self):
        print("동물이 먹고 있습니다. ")


class Cat(Animal):
    def __init__(self, name, age, breed):
        super().__init__(age)
        self.name=name
        self.breed=breed


a = Cat("aaa", 2, "Pure")
b = Cat("bbb", 3, "Pure")
c = Cat("ccc", 5, "Pure")

def get_oldest_cat(*args):
    return max(args)

age = get_oldest_cat(a.age, b.age, c.age)
print(f"가장 나이가 많은 고양이는  {age} 살입니다.")


7.
class Song:
    def __init__(self, title, artist, album, track_number):
        self.title = title
        self.artist = artist
        self.album = album
        self.track_number = track_number
        artist.add_song(self)

class Album:
    def __init__(self, title, artist, year):
        self.title = title
        self.artist = artist
        self.year = year
        self.tracks = []
        artist.add_album(self)

    def add_track(self, title, artist=None):
        if artist is None:
            artist = self.artist

        track_number = len(self.tracks)
        song = Song(title, artist, self, track_number)
        self.tracks.append(song)

class Artist:
    def __init__(self, name):
        self.name = name
        self.albums = []
        self.songs = []

    def add_album(self, album):
        self.albums.append(album)

    def add_song(self, song):
        self.songs.append(song)


class Playlist:
    def __init__(self, name):
        self.name = name
        self.songs = []

    def add_song(self, song):
        self.songs.append(song)

lee = Artist("Lee's Band")
album = Album("첫 번째 앨범", lee, 2020)
album.add_track("첫 번째 노래")
album.add_track("두 번째 노래")

playlist = Playlist("애창곡")

for song in album.tracks:
    playlist.add_song(song)