enum Shape {
    case Triangle(Float,Float)
    case Square(Float,Float)
    case Circle(Float)

    func area() -> Float {
        var area : Float = 0.0
        switch self {
        case .Triangle(let floor, let height):
            area = floor*height/2.0
        case .Square(let width, let height):
            area = width*height
        case .Circle(let radius):
            area = 3.14*radius*radius
        default:
            println("삼각형, 사각형, 원의 면적만 계산할 수 있습니다.")
        }
        return area
    }
}

let square = Shape.Square(10,7)
square.area()

let triangle = Shape.Triangle(6,9)
triangle.area()

let circle = Shape.Circle(5)
circle.area()