题解 | 两直线交点

import sys

class Point:
    def __init__(self, x=0.0, y=0.0):
        self.x = x
        self.y = y


class Line:
    def __init__(self, point_a:Point, point_b:Point):
        self.point_A = point_a 
        self.point_B = point_b 


class Coefficient:
    def __init__(self,A:float,B:float,C:float) -> None:
        self.A = A
        self.B = B
        self.C = C


def ca_line(point_A:Point, point_B:Point):
    A = 0.0
    B = 1.0
    C = 0.0

    if point_A.x == point_B.x and point_A.y == point_B.y:
        return False
    if point_A.x == point_B.x:
        A = 1.0
        B = 0.0
        C = -point_A.x
        return Coefficient(A,B,C)
    if point_A.y == point_B.y:
        A = 0.0
        B = 1.0
        C = -point_A.y
        return Coefficient(A,B,C)
    # A*x + B*y + C = 0
    m = (point_A.y - point_B.y) / (point_A.x - point_B.x)
    A = -m
    B = 1
    C = m*point_A.x -point_A.y
    return Coefficient(A,B,C)

def find_meeting_point(coef_1:Coefficient,coef_2:Coefficient):
    # TODO: 在这里输入你的代码，求直线 line_A 与 line_B 的交点
    DD = coef_1.A*coef_2.B - coef_1.B*coef_2.A
    if DD == 0:
        return (-1,-1)
    x = (coef_1.B*coef_2.C - coef_2.B*coef_1.C) / DD
    y = (coef_2.A*coef_1.C - coef_1.A*coef_2.C) / DD
    return (x,y)


if __name__ == "__main__":
    n = 1
    A_x = 0
    A_y = 0
    B_x = 0
    B_y = 0
    C_x = 0
    C_y = 0
    D_x = 0
    D_y = 0    
    for line in sys.stdin:
        a = line.split()
        if n == 1:
            A_x,A_y,B_x,B_y = int(a[0]),int(a[1]),int(a[2]),int(a[3])
            n += 1
            continue
        if n == 2:
            C_x,C_y,D_x,D_y = int(a[0]),int(a[1]),int(a[2]),int(a[3])
            n += 1
            continue            
    point_A = Point(A_x,A_y)
    point_B = Point(B_x,B_y)
    point_C = Point(C_x,C_y)
    point_D = Point(D_x,D_y)
    coef1 = ca_line(point_A,point_B)
    coef2 = ca_line(point_C,point_D)
    res = find_meeting_point(coef1,coef2)
    print(res[0],end=' ')
    print(res[1])