Problem:


  MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

Cross Points of a Circe and a Line

  For given a circle $c$ and a line $l$, print the coordinates of the cross points of them.

Input

  The input is given in the following format.

$cx\; cy\; r$

$q$

$Line_1$

$Line_2$

:

$Line_q$

  In the first line, the center coordinate of the circle and its radius are given by $cx$, $cy$ and $r$. In the second line, the number of queries $q$ is given.

  In the following $q$ lines, as queries, $Line_i$ are given ($1 \leq i \leq q$) in the following format.

$x_1\; y_1\; x_2\; y_2$

  Each line is represented by two points $p1$ and $p2$ which the line crosses. The coordinate of $p1$ and $p2$ are given by ($x1$, $y1$) and ($x2$, $y2$) respectively. All input values are given in integers.

Output

  For each query, print the coordinates of the cross points in the following rules.

If there is one cross point, print two coordinates with the same values.

Print the coordinate with smaller $x$ first. In case of a tie, print the coordinate with smaller $y$ first.

  The output values should be in a decimal fraction with an error less than 0.000001.

Constraints

$p1$ and $p2$ are different

The circle and line have at least one cross point

$1 \leq q \leq 1,000$

$-10,000 \leq cx, cy, x1, y1, x2, y2 \leq 10,000$

$1 \leq r \leq 10,000$

Sample Input and Output

Sample Input

2 1 1
2
0 1 4 1
3 0 3 3

Sample Output

1.00000000 1.00000000 3.00000000 1.00000000
3.00000000 1.00000000 3.00000000 1.00000000



Sample input:
2 1 1
2
0 1 4 1
3 0 3 3


Sample output:
1.00000000 1.00000000 3.00000000 1.00000000
3.00000000 1.00000000 3.00000000 1.00000000

Submission status: Accepted

Solution code:
import sys
from operator import itemgetter, attrgetter
from itertools import starmap
import math
readline = sys.stdin.readline
EPS = 1e-9
ONLINE_FRONT = -2
CLOCKWISE = -1
ON_SEGMENT = 0
COUNTER_CLOCKWISE = 1
ONLINE_BACK = 2
class Circle(object):
    __slots__ = ('c', 'r')
    def __init__(self, c, r):
        self.c = c
        self.r = r
class Segment(object):
    __slots__ = ('fi', 'se')
    def __init__(self, fi, se):
        self.fi = fi
        self.se = se
Line = Segment
def cross(a, b):
    return a.real * b.imag - a.imag * b.real
def dot(a, b):
    return a.real * b.real + a.imag * b.imag
def norm(base):
    return abs(base) ** 2
def project(s, p2):
    base = s.fi - s.se
    r = dot(p2 - s.fi, base) / norm(base)
    return s.fi + base * r
def reflect(s, p):
    return p + (project(s, p) - p) * 2.0
def ccw(p1, p2, p3):
    a = p2 - p1
    b = p3 - p1
    if cross(a, b) > EPS: return 1
    if cross(a, b) < -EPS: return -1
    if dot(a, b) < -EPS: return 2
    if norm(a) < norm(b): return -2
    return 0
def intersect4(p1, p2, p3, p4):
    return (ccw(p1, p2, p3) * ccw(p1, p2, p4) <= 0 and
			ccw(p3, p4, p1) * ccw(p3, p4, p2) <= 0)
def intersect2(s1, s2):
    return intersect4(s1.fi, s1.se, s2.fi, s2.se)
def getDistance(a, b):  return abs(a - b)
def getDistanceLP(l, p):
    return abs(cross(l.se - l.fi, p - l.fi) / abs(l.se - l.fi))
def getDistanceSP(s, p):
    if dot(s.se - s.fi, p - s.fi) < 0.0: return abs(p - s.fi)
    if dot(s.fi - s.se, p - s.se) < 0.0: return abs(p - s.se)
    return getDistanceLP(s, p)
def getDistances(s1, s2):
    if intersect2(s1, s2): return 0.0
    return min(getDistanceSP(s1, s2.fi), getDistanceSP(s1, s2.se),
               getDistanceSP(s2, s1.fi), getDistanceSP(s2, s1.se))
def getCrossPoint(s1, s2):
	base = s2.se - s2.fi
	d1 = abs(cross(base, s1.fi - s2.fi))
	d2 = abs(cross(base, s1.se - s2.fi))
	t = d1 / (d1 + d2)
	return s1.fi + (s1.se - s1.fi) * t
def getCrossPoints(c, l):
    pr = project(l, c.c)
    e = (l.se - l.fi) / abs(l.se - l.fi)
    base = math.sqrt(c.r * c.r - norm(pr - c.c))
    return Segment(*sorted((pr + e * base, pr - e * base), key=attrgetter('real', 'imag')))
x, y, r = map(int, readline().split())
ci = Circle(complex(x, y), r)
n = int(readline())
for _ in [0] * n:
    p0, p1 = starmap(complex, zip(*[map(int, readline().split())] * 2))
    ppp = getCrossPoints(ci, Line(p0, p1))
    print(*map('{:.10f}'.format, (ppp.fi.real, ppp.fi.imag, ppp.se.real, ppp.se.imag)))

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_D

"""
import sys
from math import sqrt
from sys import stdin
input = stdin.readline


class Point(object):
    epsilon = 1e-10

    def __init__(self, x=0.0, y=0.0):
        if isinstance(x, tuple):
            self.x = x[0]
            self.y = x[1]
        else:
            self.x = x
            self.y = y

    # ????????????
    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)

    def __sub__(self, other):
        return Point(self.x - other.x, self.y - other.y)

    def __mul__(self, other):
        return Point(other * self.x, other * self.y)

    def __truediv__(self, other):
        return Point(self.x / other, self.y / other)

    def __lt__(self, other):
        if self.x == other.x:
            return self.y < other.y
        else:
            return self.x < other.x

    def __eq__(self, other):
        from math import fabs
        if fabs(self.x - other.x) < Point.epsilon and fabs(self.y - other.y) < Point.epsilon:
            return True
        else:
            return False

    def norm(self):
        return self.x * self.x + self.y * self.y

    def __abs__(self):
        return sqrt(self.norm())

    def ccw(self, p0, p1):
        # ??????2???(p0, p1)?????????????????????????????????????????¢????????????
        a = Vector(p1 - p0)
        b = Vector(self - p0)
        if Vector.cross(a, b) > Point.epsilon:
            return 1 # 'COUNTER_CLOCKWISE'
        elif Vector.cross(a, b) < -Point.epsilon:
            return -1 # 'CLOCKWISE'
        elif Vector.dot(a, b) < -Point.epsilon:
            return 2 # 'ONLINE_BACK'
        elif a.norm() < b.norm():
            return -2 # 'ONLINE_FRONT'
        else:
            return 0 # 'ON_SEGMENT'

    def project(self, s):
        # ??????(Point)????????????s??????????????????????????????????????§?¨?(?°???±)????±???????
        base = Vector(s.p2 - s.p1)
        a = Vector(self - s.p1)
        r = Vector.dot(a, base)
        r /= base.norm()
        return s.p1 + base * r

    def reflect(self, s):
        # ??????s???????§°?????¨?????????????????¨???????§°??????????????§?¨?(????°?)????±???????
        proj = self.project(s)
        return self + (proj - self)*2

    def distance(self, s):
        # ????????¨??????s????????¢????¨??????????
        if Vector.dot(s.p2-s.p1, self-s.p1) < 0.0:
            return abs(self - s.p1)
        if Vector.dot(s.p1-s.p2, self-s.p2) < 0.0:
            return abs(self - s.p2)
        return abs(Vector.cross(s.p2-s.p1, self-s.p1) / abs(s.p2-s.p1))


class Vector(Point):
    def __init__(self, x=0.0, y=0.0):
        if isinstance(x, tuple):
            self.x = x[0]
            self.y = x[1]
        elif isinstance(x, Point):
            self.x = x.x
            self.y = x.y
        else:
            self.x = x
            self.y = y

    # ????????????
    def __add__(self, other):
        return Vector(self.x + other.x, self.y + other.y)

    def __sub__(self, other):
        return Vector(self.x - other.x, self.y - other.y)

    def __mul__(self, other):
        return Vector(other * self.x, other * self.y)

    def __truediv__(self, other):
        return Vector(other / self.x, other / self.y)

    @classmethod
    def dot(cls, a, b):
        return a.x * b.x + a.y * b.y

    @classmethod
    def cross(cls, a, b):
        return a.x * b.y - a.y * b.x

    @classmethod
    def is_orthogonal(cls, a, b):
        return Vector.dot(a, b) == 0.0

    @classmethod
    def is_parallel(cls, a, b):
        return Vector.cross(a, b) == 0.0


class Segment(object):
    def __init__(self, p1=Point(), p2=Point()):
        if isinstance(p1, Point):
            self.p1 = p1
            self.p2 = p2
        elif isinstance(p1, tuple):
            self.p1 = Point(p1[0], p1[1])
            self.p2 = Point(p2[0], p2[1])

    def intersect(self, s):
        # ????????¨??????????????????????????????????????????????????????
        ans1 = s.p1.ccw(self.p1, self.p2) * s.p2.ccw(self.p1, self.p2)
        ans2 = self.p1.ccw(s.p1, s.p2) * self.p2.ccw(s.p1, s.p2)
        return ans1 <= 0 and ans2 <= 0

    def cross_point(self, s):
        # ????????¨??????????????????????????????????????§?¨?????±???????
        base = s.p2 - s.p1
        d1 = abs(Vector.cross(base, self.p1-s.p1))
        d2 = abs(Vector.cross(base, self.p2-s.p1))
        t = d1 / (d1 + d2)
        return self.p1 + (self.p2 - self.p1) * t

    def distance(self, s):
        # ????????¨?????????????????????????????¢????±???????
        if self.intersect(s):
            return 0.0
        d1 = s.p1.distance(self)
        d2 = s.p2.distance(self)
        d3 = self.p1.distance(s)
        d4 = self.p2.distance(s)
        return min(d1, d2, d3, d4)


    @classmethod
    def is_orthogonal(cls, s1, s2):
        a = Vector(s1.p2 - s1.p1)
        b = Vector(s2.p2 - s2.p1)
        return Vector.is_orthogonal(a, b)

    @classmethod
    def is_parallel(cls, s1, s2):
        a = Vector(s1.p2 - s1.p1)
        b = Vector(s2.p2 - s2.p1)
        return Vector.is_parallel(a, b)


class Line(Segment):
    pass


class Cirle(object):
    def __init__(self, x, y=Point(), r=1.0):
        if isinstance(x, Point):
            self.c = x
            self.r = y
        elif isinstance(x, tuple):
            self.c = Point(x[0], x[1])
            self.r = r

    def cross_point(self, s):
        pr = self.c.project(s)
        e = (s.p2 - s.p1) / abs(s.p2 - s.p1)
        base = sqrt(self.r * self.r - (pr - self.c).norm())
        return pr + e * base, pr - e * base


def main(args):
    x, y, r = map(int, input().split())
    q = int(input())
    c = Cirle(Point(x, y), r)
    for _ in range(q):
        x1, y1, x2, y2 = map(int, input().split())
        p1 = Point(x1, y1)
        p2 = Point(x2, y2)
        s = Segment(p1, p2)
        ans1, ans2 = c.cross_point(s)
        if ans1.x < ans2.x:
            print('{:.8f} {:.8f} {:.8f} {:.8f}'.format(ans1.x, ans1.y, ans2.x, ans2.y))
        elif ans1.x == ans2.x and ans1.y <= ans2.y:
            print('{:.8f} {:.8f} {:.8f} {:.8f}'.format(ans1.x, ans1.y, ans2.x, ans2.y))
        else:
            print('{:.8f} {:.8f} {:.8f} {:.8f}'.format(ans2.x, ans2.y, ans1.x, ans1.y))


if __name__ == '__main__':
    main(sys.argv[1:])

Submission status: Accepted

Solution code:
from math import sqrt
cx,cy,r = map(int,input().split())
c = [cx, cy]
q = int(input())

class Line:pass

def dot(a, b):
    return sum([i * j for i,j in zip(a, b)])
def add(a,b):
    return [a[0] + b[0],a[1] + b[1]]
def sub(a, b):
    return [a[0] - b[0],a[1] - b[1]]
def multi(k, a):
    return [k*a[0],k*a[1]]
def cross(a, b):
    return  a[0] * b[1] - a[1] * b[0]
def norm(a):
    return sqrt(a[0] ** 2 + a[1] ** 2)    
def proj(p, l):
    base = sub(l.p2, l.p1)
    hypo = sub(p, l.p1)
    t = dot(hypo,base) / norm(base)
    return add(l.p1, multi(t/norm(base), base))
    
for i in range(q):
    x1,y1,x2,y2 = map(int, input().split())
    l = Line()
    l.p1 = [x1,y1]
    l.p2 = [x2,y2]
    pr = proj(c, l)
    e = multi(1/norm(sub(l.p2, l.p1)),sub(l.p2, l.p1))
    e2 = multi(-1, e)
    base = sqrt(r**2 - norm(sub(pr,c))**2)
    a = add(pr, multi(base, e))
    b = add(pr, multi(base, e2))
    ans = [a,b]
    ans = sorted(ans, key=lambda x: (x[0],x[1]))
    print(' '.join([str(round(i,8)) for o in ans for i in o]))

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-

import collections
import math


class Vector2(collections.namedtuple("Vector2", ["x",  "y"])):

    def __add__(self, other):
        return Vector2(self.x + other.x, self.y + other.y)

    def __sub__(self, other):
        return Vector2(self.x - other.x, self.y - other.y)

    def __mul__(self, scalar):
        return Vector2(self.x * scalar, self.y * scalar)

    def __neg__(self):
        return Vector2(-self.x, -self.y)

    def __pos__(self):
        return Vector2(+self.x, +self.y)

    def __abs__(self):  # norm
        return math.sqrt(float(self.x * self.x + self.y * self.y))

    def __truediv__(self, scalar):
        return Vector2(self.x/scalar, self.y/scalar)

    def abs2(self):
        return float(self.x * self.x + self.y * self.y)

    def dot(self, other):  # dot product
        return self.x * other.x + self.y * other.y

    def cross(self, other):  # cross product
        return self.x * other.y - self.y * other.x


def getDistanceSP(segment, point):
    p = point
    p1, p2 = segment
    if (p2 - p1).dot(p - p1) < 0:
        return abs(p - p1)
    if (p1 - p2).dot(p - p2) < 0:
        return abs(p - p2)
    return abs((p2 - p1).cross(p - p1)) / abs(p2 - p1)


def getDistance(s1, s2):
    a, b = s1
    c, d = s2
    if intersect(s1, s2):  # intersect
        return 0
    return min(getDistanceSP(s1, c), getDistanceSP(s1, d), getDistanceSP(s2, a), getDistanceSP(s2, b))


def ccw(p0, p1, p2):
    a = p1 - p0
    b = p2 - p0
    if a.cross(b) > 0:
        return 1  # COUNTER_CLOCKWISE
    elif a.cross(b) < 0:
        return -1  # CLOCKWISE
    elif a.dot(b) < 0:
        return 2  # ONLINE_BACK
    elif abs(a) < abs(b):
        return -2  # ONLINE_FRONT
    else:
        return 0  # ON_SEGMENT


def intersect(s1, s2):
    a, b = s1
    c, d = s2
    return ccw(a, b, c) * ccw(a, b, d) <= 0 and ccw(c, d, a) * ccw(c, d, b) <= 0


def project(l, p):
    p1, p2 = l
    base = p2 - p1
    hypo = p - p1
    return p1 + base * (hypo.dot(base) / abs(base)**2)


class Circle():
    def __init__(self, c, r):
        self.c = c
        self.r = r


def getCrossPoints(c, l):
    pr = project(l, c.c)
    p1, p2 = l
    e = (p2 - p1) / abs(p2 - p1)
    base = math.sqrt(c.r*c.r - (pr - c.c).abs2())
    return [pr + e * base, pr - e * base]

if __name__ == '__main__':

    a, b, r = map(int, input().split())
    c = Circle(Vector2(a, b), r)
    n = int(input())
    res = []
    for _ in range(n):
        ps = list(map(int, input().split()))
        l = [Vector2(ps[0], ps[1]), Vector2(ps[2], ps[3])]

        ans = getCrossPoints(c, l)
        ans = sorted(ans, key=lambda x: (x.x, x.y))
        res.append(ans)
        
    for ans in res:
        print("{:.8f} {:.8f} {:.8f} {:.8f}".format(ans[0].x, ans[0].y, ans[1].x, ans[1].y))

Submission status: Accepted

Solution code:
import math

class Vector:
    def __init__(self,x,y):
        self.x = x
        self.y = y
        
    def __add__(self,other):
        return Vector(self.x+other.x,self.y+other.y)
    
    def __sub__(self,other):
        return Vector(self.x-other.x,self.y-other.y)
    
    def __mul__(self,scalar):
        return Vector(self.x*scalar,self.y*scalar)
    def __rmul__(self, scalar):
        return Vector(self.x*scalar,self.y*scalar)
    
   
    def __repr__(self):
        return str([self.x,self.y])
        
    def norm_2(self):
        return dot(self,self)
    
    def norm(self):
        return math.sqrt(self.norm_2())
    
def v_sum(v1,v2):
    return Vector(v1.x+v2.x,v1.y+v2.y) 
def scalar_multi(k,v):
    return Vector(k*v.x,k*v.y)
def v_diff(v1,v2):
    return v_sum(v1,scalar_multi(-1,v2))
    
def dot(vector1,vector2):
    return vector1.x*vector2.x+vector1.y*vector2.y

def cross(vector1,vector2):
    return vector1.x*vector2.y-vector1.y*vector2.x

cx,cy,r = map(int,input().split())
c = Vector(cx,cy)
q = int(input())

for i in range(q):
    x1,y1,x2,y2 = map(int,input().split())
    p1 = Vector(x1,y1)
    p2 = Vector(x2,y2)
    d = p2-p1
    m = p1+(dot(c-p1,d)/d.norm_2()*d)
    #h = abs(cross(c-p1,d))/d.norm()
    l = math.sqrt(r**2-(m-c).norm_2())
    
    a = m-(l/d.norm()*d)
    b = m+(l/d.norm()*d)   
    
    if abs(a.x)<10**(-9):
        a.x = 0
    if abs(a.y)<10**(-9):
        a.y = 0
    if abs(b.x)<10**(-9):
        b.x = 0
    if abs(b.y)<10**(-9):
        b.y = 0
        
    if a.x<b.x:
        print('{} {} {} {}'.format(a.x,a.y,b.x,b.y))
    elif a.x>b.x:
        print('{} {} {} {}'.format(b.x,b.y,a.x,a.y))
    else:
        if a.y<b.y:
            print('{} {} {} {}'.format(a.x,a.y,b.x,b.y))
        else:
            print('{} {} {} {}'.format(b.x,b.y,a.x,a.y))

Submission status: Accepted

Solution code:
import math
EPS = 10**(-9)
def is_equal(a,b):
    return abs(a-b) < EPS

def norm(v,i=2):
    ret = 0
    n = len(v)
    for j in range(n):
        ret += abs(v[j])**i
    return math.pow(ret,1/i)

class Vector(list):
    """
    ベクトルクラス
    対応演算子
    +  : ベクトル和 
    -  : ベクトル差
    *  : スカラー倍、または内積
    /  : スカラー除法
    ** : 外積
    += : ベクトル和
    -= : ベクトル差
    *= : スカラー倍
    /= : スカラー除法

    メソッド
    self.norm(i) : L{i}ノルムを計算
    """
    def __add__(self,other):
        n = len(self)
        ret = [0]*n
        for i in range(n):
            ret[i] = super().__getitem__(i) + other.__getitem__(i)
        return self.__class__(ret)
    
    def __radd__(self,other):
        n = len(self)
        ret = [0]*n
        for i in range(n):
            ret[i] = other.__getitem__(i) + super().__getitem__(i)
        return self.__class__(ret)
    
    def __iadd__(self, other):
        n = len(self)
        for i in range(n):
            self[i] += other.__getitem__(i)
        return self

    def __sub__(self,others):
        n = len(self) 
        ret = [0]*n
        for i in range(n):
            ret[i] = super().__getitem__(i) - others.__getitem__(i)
        return self.__class__(ret)

    def __isub__(self, other):
        n = len(self)
        for i in range(n):
            self[i] -= other.__getitem__(i)
        return self

    def __rsub__(self,others):
        n = len(self) 
        ret = [0]*n
        for i in range(n):
            ret[i] = others.__getitem__(i) - super().__getitem__(i)
        return self.__class__(ret)
    
    def __mul__(self,other):
        n = len(self)
        if isinstance(other,list):
            ret = 0
            for i in range(n):
                ret += super().__getitem__(i)*other.__getitem__(i)
            return ret
        else:
            ret = [0]*n
            for i in range(n):
                ret[i] = super().__getitem__(i)*other
            return self.__class__(ret)

    def __rmul__(self,other):
        n = len(self)
        if isinstance(other,list):
            ret = 0
            for i in range(n):
                ret += super().__getitem__(i)*other.__getitem__(i)
            return ret
        else:
            ret = [0]*n
            for i in range(n):
                ret[i] = super().__getitem__(i)*other
            return self.__class__(ret)
    
    
    def __truediv__(self,other):
        """
        ベクトルのスカラー除法
        Vector/scalar
        """
        n = len(self)
        ret = [0]*n
        for i in range(n):
            ret[i] = super().__getitem__(i)/other
        return self.__class__(ret)
    
    def norm(self,i):
        """
        L{i}ノルム
        self.norm(i)
        """
        return norm(self,i)
    
    def __pow__(self,other):
        """
        外積
        self**other
        """
        n = len(self)
        ret = [0]*3
        x = self[:]
        y = other[:]
        if n == 2:
            x.append(0)
            y.append(0)
        if n == 2 or n == 3:
            for i in range(3):
                ret[0],ret[1],ret[2] = x[1]*y[2]-x[2]*y[1],x[2]*y[0]-x[0]*y[2],x[0]*y[1]-x[1]*y[0]
            ret = Vector(ret)
            if n == 2:
                return ret
            else:
                return ret

class Segment:
    """
    線分クラス

    methods
    length()                 :
    get_unit_vec()           : 
    projection(vector)       :
    is_vertical(segment)     :
    is_horizontal(segment)   :
    reflection()             :
    include()                :
    distance()               :
    ccw()                    :
    intersect()              :
    intersect_point          :
    """
    def __init__(self,v1,v2):
        self.v1 = v1
        self.v2 = v2
    
    def length(self):
        return norm(self.v1-self.v2)

    def get_unit_vec(self):
        #方向単位ベクトル
        dist = norm(self.v2-self.v1)
        if dist != 0:
            return (self.v2-self.v1)/dist
        else:
            return False
    
    def projection(self,vector):
        #射影点(線分を直線と見たときの)
        unit_vec = self.get_unit_vec()
        t = unit_vec*(vector-self.v1)
        return self.v1 + t*unit_vec
    
    def is_vertical(self,other):
        #線分の直交判定
        return is_equal(0,self.get_unit_vec()*other.get_unit_vec())
    
    def is_horizontal(self,other):
        #線分の平行判定
        return is_equal(0,self.get_unit_vec()**other.get_unit_vec())
    
    def reflection(self,vector):
        #反射点(線分を直線と見たときの)
        projection = self.projection(vector)
        v = projection - vector
        return projection + vector
    
    def include(self,vector):
        #線分が点を含むか否か
        proj = self.projection(vector)
        if not is_equal(norm(proj-vector),0):
            return False
        else:
            n = len(self.v1)
            f = True
            for i in range(n):
                f &= ((self.v1[i] <= vector[i] <= self.v2[i]) or (self.v2[i] <= vector[i] <=self.v1[i]))
            return f
    
    def distance(self,other):
        #点と線分の距離
        if isinstance(other,Vector):
            proj = self.projection(other)
            if self.include(proj):
                return norm(proj-other)
            else:
                ret = []
                ret.append(norm(self.v1-other))
                ret.append(norm(self.v2-other))
                return min(ret)

    def ccw(self,vector):
        """
        線分に対して点が反時計回りの位置にある(1)か時計回りの位置にある(-1)か線分上にある(0)か
        ただし、直線上にはあるが線分上にはない場合は反時計回りの位置にあると判定して1を返す。
        """
        direction = self.v2 - self.v1
        v = vector - self.v1
        if self.include(vector):
            return 0
        else:
            cross = direction**v
            if cross[2] <= 0:
                return 1
            else:
                return -1
    
    def intersect(self,segment):
        """
        線分の交差判定
        """
        ccw12 = self.ccw(segment.v1)
        ccw13 = self.ccw(segment.v2)
        ccw20 = segment.ccw(self.v1)
        ccw21 = segment.ccw(self.v2)

        if ccw12*ccw13*ccw20*ccw21 == 0:
            return True
        else:
            if ccw12*ccw13 < 0 and ccw20*ccw21 < 0:
                return True
            else:
                return False
    
    def intersect_point(self,segment):
        """
        線分の交点
        """
        d1 = norm(self.projection(segment.v1) - segment.v1)
        d2 = norm(self.projection(segment.v2) - segment.v2)
        return segment.v1 + (d1/(d1 + d2)) * (segment.v2 - segment.v1)


class Line(Segment):
    """
    直線クラス
    """
    #直線上に点が存在するか否か
    def include(self,vector):
        proj = self.projection(vector)
        return is_equal(norm(proj-vector),0)
    
    def distance(self,vector):
        return norm(self.projection(vector) - vector)


class Circle():
    def __init__(self,vector,r):
        self.c = vector
        self.r = r
    
    def intersect_point(self,other):
        if isinstance(other,Line):
            if other.distance(self.c) > self.r:
                return False
            else:
                d = other.distance(self.c)
                proj = other.projection(self.c)
                unit_v = other.get_unit_vec()
                t = (self.r**2 - d**2)**0.5
                return proj + t*unit_v, proj - t*unit_v


cx,cy,r = map(int,input().split())
circle = Circle(Vector([cx,cy]),r)
q = int(input())
lines = [0]*q
for i in range(q):
    x1,y1,x2,y2 = map(int,input().split())
    lines[i] = Line(Vector([x1,y1]),Vector([x2,y2]))

for i in range(q):
    ic1,ic2 = circle.intersect_point(lines[i])
    ics = [ic1,ic2]
    ics.sort()
    print("{:.7f} {:.7f} {:.7f} {:.7f}".format(*ics[0],*ics[1]))

Submission status: Accepted

Solution code:
import math

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)
    def __sub__(self, other):
        return Point(self.x - other.x, self.y - other.y)
    def __mul__(self, other):
        return Point(self.x * other, self.y * other)
    def __truediv__(self, other):
        return Point(self.x / other, self.y / other)
    def __repr__(self):
        return str(round(self.x, 8)) + ' ' + str(round(self.y, 8))
    def __lt__(self, other):
        if self.x == other.x:
            return self.y < other.y
        else:
            return self.x < other.x

class Vector(Point):
    pass

class Line:
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2

class Segment(Line):
    pass

class Circle:
    def __init__(self, c, r):
        self.c = c
        self.r = r

def points_to_vector(p1, p2):
    x = p1.x - p2.x
    y = p1.y - p2.y
    return Vector(x, y)

def vector(p):
    return Vector(p.x, p.y)

def dot(v1, v2):
    return v1.x * v2.x + v1.y * v2.y

def cross(v1, v2):
    return v1.x * v2.y - v1.y * v2.x

def norm(v):
    return v.x**2 + v.y**2

def distance(v):
    return math.sqrt(norm(v))

def project(s, p):
    base = points_to_vector(s.p1, s.p2)
    hypo = points_to_vector(p, s.p1)
    r = dot(hypo, base) / norm(base)
    return s.p1 + base * r

def reflect(s, p):
    return p + (project(s, p) -p) * 2

def get_distance(s1, s2):
    if intersect_s(s1, s2):
        return 0
    d1 = get_distance_sp(s1, s2.p1)
    d2 = get_distance_sp(s1, s2.p2)
    d3 = get_distance_sp(s2, s1.p1)
    d4 = get_distance_sp(s2, s1.p2)
    return min(d1, min(d2, min(d3, d4)))

def get_distance_pp(p1, p2):
    return distance(p1 - p2)

def get_distance_lp(l, p):
    return abs(cross(l.p2 - l.p1, p - l.p1) / distance(l.p2 - l.p1))

def get_distance_sp(s, p):
    if dot(s.p2 - s.p1, p - s.p1) < 0:
        return distance(p - s.p1)
    elif dot(s.p1 - s.p2, p - s.p2) < 0:
        return distance(p - s.p2)
    else:
        return get_distance_lp(s, p)

def ccw(p0, p1, p2):
    EPS = 1e-10
    COUNTER_CLOCKWISE = 1
    CLOCKWISE = -1
    ONLINE_BACK = 2
    ONLINE_FRONT = -2
    ON_SEGMENT = 0
    v1 = p1 - p0
    v2 = p2 - p0
    if cross(v1, v2) > EPS:
        return COUNTER_CLOCKWISE
    elif cross(v1, v2) < -EPS:
        return CLOCKWISE
    elif dot(v1, v2) < -EPS:
        return ONLINE_BACK
    elif norm(v1) < norm(v2):
        return ONLINE_FRONT
    else:
        return ON_SEGMENT

def intersect_p(p1, p2, p3, p4):
    return ccw(p1, p2, p3) * ccw(p1, p2, p4) <= 0 and ccw(p3, p4, p1) * ccw(p3, p4, p2) <= 0

def intersect_s(s1, s2):
    return intersect_p(s1.p1, s1.p2, s2.p1, s2.p2)

def get_cross_point(s1, s2):
    base = s2.p2 - s2.p1
    d1 = abs(cross(base, s1.p1 - s2.p1))
    d2 = abs(cross(base, s1.p2 - s2.p1))
    t = d1 / (d1 + d2)
    return s1.p1 + (s1.p2 - s1.p1) * t

def get_cross_points(c, l):
    pr = project(l, c.c)
    e = (l.p2 - l.p1) / distance(l.p2 - l.p1)
    base = math.sqrt(c.r**2 - norm(pr - c.c))
    return pr + e * base, pr - e * base

import sys
# sys.stdin = open('input.txt')

temp = list(map(int, input().split()))
c = Circle(Point(temp[0], temp[1]), temp[2])
q = int(input())

for i in range(q):
    temp = list(map(int, input().split()))
    points = []
    for j in range(0, 4, 2):
        points.append(Point(temp[j], temp[j+1]))
    l = Line(points[0], points[1])
    ans = get_cross_points(c, l)
    print(min(ans), max(ans))

Submission status: Accepted

Solution code:
from functools import singledispatch
import math

EPS = 1e-10

COUNTER_CLOCKWISE = 1
CLOCKWISE = -1
ONLINE_BACK = 2
ONLINE_FRONT = -2
ON_SEGMENT = 0

class Segment():
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2

class Circle():
    def __init__(self, c, r):
        self.c = c
        self.r = r

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

    def __add__(self, point):
        # + 演算子での挙動を指定
        return Point(self.x+point.x, self.y+point.y)

    def __sub__(self, point):
        # - 演算子での挙動を指定
        return Point(self.x-point.x, self.y-point.y)

    def __mul__(self, a):
        # * 演算子での挙動を指定
        return Point(a*self.x, a*self.y)

    def __truediv__(self, a):
        # / 演算子での挙動を指定
        return Point(self.x/a, self.y/a)

    def __abs__(self):
        # abs関数での挙動を指定
        return math.sqrt(self.norm())

    def norm(self):
        return self.x**2+self.y**2

    def __eq__(self, point):
        # == 演算子での挙動を指定
        return abs(self.x-point.x) < EPS and abs(self.y-point.y) <EPS

def dot(a, b):
    return a.x*b.x+a.y*b.y

def cross(a, b):
    return a.x*b.y - a.y*b.x

def isOrthogonal(a, b):
    return dot(a, b) == 0

def isParallel(a, b):
    return cross(a, b) == 0

def project(s, p):
    #s: Segment(), p: Point()
    base = s.p2 - s.p1
    r = dot(p-s.p1, base)/base.norm()
    return s.p1+base*r

def reflect(s, p):
    return p+(project(s, p)-p)*2

@singledispatch
def get_distance(a, b):
    return abs(a-b)

def get_distance_lp(l, p):
    return abs(cross(l.p2-l.p1, p-l.p1)/abs(l.p2-l.p1))

def get_distance_sp(s, p):
    if dot(s.p2-s.p1, p-s.p1) < 0:
        return abs(p-s.p1)
    if dot(s.p1-s.p2, p-s.p2) < 0:
        return abs(p-s.p2)
    return get_distance_lp(s, p)
    
@get_distance.register(Segment)
def _(s1, s2):
    if intersect(s1, s2):
        return 0
    return min([get_distance_sp(s1, s2.p1), get_distance_sp(s1, s2.p2),
                get_distance_sp(s2, s1.p1), get_distance_sp(s2, s1.p2)])

def ccw(p0, p1, p2):
    a = p1 - p0
    b = p2 - p0
    if cross(a, b) > EPS:
        return COUNTER_CLOCKWISE
    if cross(a, b) < -EPS:
        return CLOCKWISE
    if dot(a, b) < -EPS:
        return ONLINE_BACK
    if a.norm() < b.norm():
        return ONLINE_FRONT
    return ON_SEGMENT

@singledispatch
def intersect(p1, p2, p3, p4):
    return (ccw(p1, p2, p3)*ccw(p1, p2, p4) <= 0
            and ccw(p3, p4, p1)*ccw(p3, p4, p2) <= 0)

@intersect.register(Segment)
def _(s1, s2):
    return intersect(s1.p1, s1.p2, s2.p1, s2.p2)

def get_cross_point(s1, s2):
    base = s2.p2 - s2.p1
    d1 = abs(cross(base, s1.p1-s2.p1))
    d2 = abs(cross(base, s1.p2-s2.p1))
    t = d1/(d1+d2)
    return s1.p1 + (s1.p2-s1.p1)*t

def get_cross_points(c, l):
    # 以下のコードは、新しいintersect関数を作る必要があり(おそらくpython3.7以上必須)、手間取るので割愛します。
    # assert(intersect(c, l))
    pr = project(l, c.c)
    e = (l.p2 - l.p1)/abs(l.p2-l.p1)
    base = (c.r**2-(pr-c.c).norm())**0.5
    return (pr+e*base, pr-e*base)
    

if __name__ == '__main__':
    from sys import stdin
    input = stdin.readline

    cx, cy, r = map(int, input().split())
    center = Point(cx, cy)
    c = Circle(center, r)

    q = int(input())
    for _ in range(q):
        x1, y1, x2, y2 = map(int, input().split())
        p1 = Point(x1, y1)
        p2 = Point(x2, y2)
        l = Segment(p1, p2)
        ans1, ans2 = get_cross_points(c, l)
        for ans in [ans1, ans2]:
            if round(ans.x, 10) == 0:
                ans.x = 0
            if round(ans.y, 10) == 0:
                ans.y = 0
        if ans1.x < ans2.x or (ans1.x == ans2.x and ans1.y < ans2.y):
            
            print(ans1.x, ans1.y, ans2.x, ans2.y)
        else:
            print(ans2.x, ans2.y, ans1.x, ans1.y)