CGL_2_A: Parallel/Orthogonal
では問題に
変数に型ヒントをつけるにはどうするのがいいのかな
それとも関数の型ヒントでカバーできるように書いていくほうがスジがいいのか
PEP 484には型コメントの書き方だけ書いてある
Type comments
No first-class syntax support for explicitly marking variables as being of a specific type is added by this PEP. To help with type inference in complex cases, a comment of the following format may be used:
でもどっかでx: SomeTypeみたいなの見たことあった気がするんだけど
実際、こんなファイルをmypyにかけると
def foo(x: int) -> int:
y: str = x
return y指摘してくれるし
$ mypy type-hint.py
type-hint.py:6: error: Incompatible types in assignment (expression has type "int", variable has type "str")
type-hint.py:7: error: Incompatible return value type (got "str", expected "int")あった
PEP 526 -- Syntax for Variable Annotations | Python.org
これはPython 3.6からなのか
使っていこう
問題自体は大したことはなくて、
平行は外積の大きさが0、直交は内積の大きさが0で判定してやればよい
直交や平行もライブラリの方に入れて、本体はこれだけ
from shape import float_equal, Point, Vector, Segment
def classify(s1: Segment, s2: Segment) -> int:
if s1.is_parallel(s2):
return 2
elif s1.is_orthogonal(s2):
return 1
else:
return 0
def main() -> None:
q = int(input())
for _ in range(q):
s1, s2 = Segment(), Segment()
s1.p1.x, s1.p1.y, s1.p2.x, s1.p2.y, \
s2.p1.x, s2.p1.y, s2.p2.x, s2.p2.y = \
[int(x) for x in input().split()]
print(classify(s1, s2))
if __name__ == "__main__":
main()こういうところはもうちょっとかっこいい書き方がないものかな
s1, s2 = [int(x) for x in input().split()]とか書けたらいいのに
s1.p1.x, s1.p1.y, s1.p2.x, s1.p2.y, \
s2.p1.x, s2.p1.y, s2.p2.x, s2.p2.y = \
[int(x) for x in input().split()]クラスの実装
なおdotやcrossも結局クラスに入れました
from typing import List
from math import sqrt
EPS = 1e-10
def float_equal(x: float, y: float) -> bool:
return abs(x - y) < EPS
class Point:
def __init__(self, x: float=0.0, y: float=0.0) -> None:
self.x = x
self.y = y
def __repr__(self) -> str:
return "Point({}, {})".format(self.x, self.y)
def __eq__(self, other: object) -> bool:
if not isinstance(other, Point):
return NotImplemented
return float_equal(self.x, other.x) and \
float_equal(self.y, other.y)
def __add__(self, other: 'Point') -> 'Point':
return Point(self.x + other.x, self.y + other.y)
def __sub__(self, other: 'Point') -> 'Point':
return Point(self.x - other.x, self.y - other.y)
def __mul__(self, k: float) -> 'Point':
return Point(self.x * k, self.y * k)
def __rmul__(self, k: float) -> 'Point':
return self * k
def __truediv__(self, k: float) -> 'Point':
return Point(self.x / k, self.y / k)
def __lt__(self, other: 'Point') -> bool:
return self.y < other.y \
if abs(self.x - other.x) < EPS \
else self.x < other.x
def norm(self):
return self.x * self.x + self.y * self.y
def abs(self):
return sqrt(self.norm())
def dot(self, other: 'Point') -> float:
return self.x * other.x + self.y * other.y
def cross(self, other: 'Point') -> float:
return self.x * other.y - self.y * other.x
def is_orthogonal(self, other: 'Point') -> bool:
return float_equal(self.dot(other), 0.0)
def is_parallel(self, other: 'Point') -> bool:
return float_equal(self.cross(other), 0.0)
Vector = Point
class Segment:
def __init__(self, p1: Point = None, p2: Point = None) -> None:
self.p1: Point = Point() if p1 is None else p1
self.p2: Point = Point() if p2 is None else p2
def __repr__(self) -> str:
return "Segment({}, {})".format(self.p1, self.p2)
def __eq__(self, other: object) -> bool:
if not isinstance(other, Segment):
return NotImplemented
return self.p1 == other.p1 and self.p2 == other.p2
def vector(self):
return self.p2 - self.p1
def is_orthogonal(self, other: 'Segment') -> bool:
return self.vector().is_orthogonal(other.vector())
def is_parallel(self, other: 'Segment') -> bool:
return self.vector().is_parallel(other.vector())ふー
じゃあジャッジしてもらおう
ってこれ、どうやって貼るんだよ
２ファイル分は貼れません
えーと
クラス定義を貼って、その下に本体のimportを削った残りを貼るくらいで済んだ
よかった
