题解 | #图形面积#

import math

# 定义一个父类Square，表示正方形
class Square:
    def __init__(self,r):
        self.r = r
    
    def getArea(self):
        return int(math.pow(int(self.r), 2))

# 定义子类Rectangle
class Rectangle(Square):
    def getArea(self):
        tmp = str(self.r).split(" ")
        return int(tmp[0])*int(tmp[1])
# 定义子类Circular
class Circular(Square):
    def getArea(self):
        self.r = int(self.r)
        return float(f'%.3f' %(math.pi*pow(self.r,2)))
                     
# 定义子类Triangle
class Triangle(Square):
    def getArea(self):
        self.r = int(self.r)
        p = (self.r*3)/2
        s = (p*(p-self.r)*(p-self.r)*(p-self.r)) ** 0.5
        return float('%.3f' %s)

kind = input()
r = input()
if kind == 'Square':
    print(Square(r).getArea())
elif kind == 'Rectangle':
    print(Rectangle(r).getArea())
elif kind == 'Circular':
    print(Circular(r).getArea())
else:
    print(Triangle(r).getArea())