Problem:


Intersection

For given two segments s1 and s2, print "1" if they are intersect, "0" otherwise.

s1 is formed by end points p0 and p1, and
s2 is formed by end points p2 and p3.

Input

The entire input looks like:

q (the number of queries)
1st query
2nd query
...
qth query

Each query consists of integer coordinates of end points of s1 and s2 in the following format:

xp0 yp0 xp1 yp1 xp2 yp2 xp3 yp3

Output

For each query, print "1" or "0".

Constraints

1 ≤ q ≤ 1000

-10000 ≤ xpi, ypi ≤ 10000

p0 &ne; p1 and
p2 &ne; p3.

Sample Input 1

3
0 0 3 0 1 1 2 -1
0 0 3 0 3 1 3 -1
0 0 3 0 3 -2 5 0

Sample Output 1

1
1
0



Sample input:
3
0 0 3 0 1 1 2 -1
0 0 3 0 3 1 3 -1
0 0 3 0 3 -2 5 0


Sample output:
1
1
0

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 __floordiv__(self, other):
        return Point(self.x / other, self.y / other)
    def __repr__(self):
        return str(self.x) + ' ' + str(self.y)

class Vector(Point):
    pass

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

class Segment(Line):
    pass

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):
#     #TODO: Define intersect()
#     if insersect(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 distance(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)


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

q = int(input())
for i in range(q):
    temp = list(map(int, input().split()))
    points = []
    for j in range(0, 8, 2):
        points.append(Point(temp[j], temp[j+1]))
    s1 = Segment(points[0], points[1])
    s2 = Segment(points[2], points[3])
    if intersect_s(s1, s2):
        print(1)
    else:
        print(0)

Submission status: Accepted

Solution code:
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 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

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)

def intersect(s1, s2):
    return True
    
def get_distance(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

from functools import singledispatch
@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)


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

    

    q = int(input())
    for _ in range(q):
        x0, y0, x1, y1, x2, y2, x3, y3 = map(int, input().split())
        p0 = Point(x0, y0)
        p1 = Point(x1, y1)
        p2 = Point(x2, y2)
        p3 = Point(x3, y3)
        s1 = Segment(p0, p1)
        s2 = Segment(p2, p3)
        if intersect(s1, s2):
            print(1)
        else:
            print(0)

Submission status: Accepted

Solution code:
#!/usr/bin/env python

q = input()

for loop in range(q):
    x0, y0, x1, y1, x2, y2, x3, y3 = map(int, raw_input().split())
    # ax + by = c
    a1, b1, c1 = [y1 - y0, x0 - x1, x0 * (y1 - y0) - y0 * (x1 - x0)]
    a2, b2, c2 = [y3 - y2, x2 - x3, x2 * (y3 - y2) - y2 * (x3 - x2)]
    det = a1 * b2 - b1 * a2
    # parallel
    if det == 0:
        if x0 * a1 + y0 * b1 != x2 * a1 + y2 * b1: # not collinear
            print 0
        elif max(x0, x1) < min(x2, x3) or max(x2, x3) < min(x0, x1) \
            or max(y0, y1) < min(y2, y3) or max(y2, y3) < min(y0, y1): # not overlap
            print 0
        else: # overlap
            print 1
        continue

    if (a1 * x2 + b1 * y2 - c1) * (a1 * x3 + b1 * y3 - c1) <= 0 and \
        (a2 * x0 + b2 * y0 - c2) * (a2 * x1 + b2 * y1 - c2) <= 0:
        print 1
    else:
        print 0

Submission status: Accepted

Solution code:
def cross(v1,v2):
	return v1.real*v2.imag-v1.imag*v2.real

def isOnSegment(p1,p2,p):
	return abs(p1-p)+abs(p2-p)-abs(p1-p2)<=1e-8

def isIntersection(p1,p2,p3,p4):
	if cross(p2-p1,p4-p3)==0:
		return any(isOnSegment(q1,q2,q3)for q1,q2,q3 in ((p1,p2,p3),(p1,p2,p4),(p3,p4,p1),(p3,p4,p2)))
	return cross(p2-p1,p3-p1)*cross(p2-p1,p4-p1)<=1e-8>=cross(p4-p3,p1-p3)*cross(p4-p3,p2-p3)

import sys
input = sys.stdin.buffer.readline
ans=[]
for _ in range(int(input())):
	m=map(int,input().split())
	ans.append(int(isIntersection(*[complex(x,y)for x,y in zip(*[iter(m)]*2)])))
print("\n".join(map(str,ans)))

Submission status: Accepted

Solution code:
from math import pi, cos, sin, atan2
EPS = 10**(-9)

def eq(value1, value2):
    return abs(value1-value2) <= EPS

class Point():
    def __init__(self, x, y):
        self.x = x
        self.y = y
        self.arg = atan2(y, x) # -PI ~ PI
    
    def __str__(self):
        return "{0:.8f} {1:.8f}".format(self.x, self.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, scal):
        return Point(self.x*scal, self.y*scal)
    
    def __truediv__(self, scal):
        return Point(self.x/scal, self.y/scal)
    
    def __eq__(self, other):
        return eq(self.x, other.x) and eq(self.y, other.y)

    # 原点からの距離
    def __abs__(self):
        return (self.x**2+self.y**2)**0.5
    
# 原点を中心にrad角だけ回転した点
def Rotation(vec: Point, rad):
    return Point(vec.x*cos(rad)-vec.y*sin(rad), vec.x*sin(rad)+vec.y*cos(rad))


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


class Line():
    # 点a, bを通る
    def __init__(self, a, b):
        self.a = a
        self.b = b
        self.arg = (a-b).arg % pi
    
    def __str__(self):
        return "[({0}, {1}) - ({2}, {3})]".format(self.a.x, self.a.y, self.b.x, self.b.y)

    # pointを通って平行
    def par(self, point):
        return Line(point, point+(self.a-self.b))

    # pointを通って垂直
    def tan(self, point):
        return Line(point, point + Rotation(self.a-self.b, pi/2))


class Segment(Line):
    def __init__(self, a, b):
        super().__init__(a, b)


# 符号付き面積
def cross(vec1: Point, vec2: Point):
    return vec1.x*vec2.y - vec1.y*vec2.x

# 内積
def dot(vec1: Point, vec2: Point):
    return vec1.x*vec2.x + vec1.y*vec2.y

# 点a->b->cの回転方向
def ccw(a, b, c):
    if cross(b-a, c-a) > EPS: return +1 # COUNTER_CLOCKWISE
    if cross(b-a, c-a) < -EPS: return -1 # CLOCKWISE
    if dot(c-a, b-a) < -EPS: return +2 # c -> a -> b
    if abs(b-a) < abs(c-a): return -2 # a -> b -> c
    return 0 # a -> c -> b


# pのlへの射影
def projection(l, p):
    t = dot(l.b-l.a, p-l.a) / abs(l.a-l.b)**2
    return l.a + (l.b-l.a)*t

# pのlによる反射
def reflection(l, p):
    return p + (projection(l, p) - p)*2

def isPararell(l1, l2):
    return eq(cross(l1.a-l1.b, l2.a-l2.b), 0)

def isVertical(l1, l2):
    return eq(dot(l1.a-l1.b, l2.a-l2.b), 0)


def isIntersect_lp(l, p):
    return abs(ccw(l.a, l.b, p)) != 1

def isIntersect_ll(l1, l2):
    return not isPararell(l1, l2) or isIntersect_lp(l1, l2.a)

def isIntersect_sp(s, p):
    return ccw(s.a, s.b, p) == 0

def isIntersect_ss(s1, s2):
    return ccw(s1.a, s1.b, s2.a)*ccw(s1.a, s1.b, s2.b) <= 0 and ccw(s2.a, s2.b, s1.a)*ccw(s2.a, s2.b, s1.b) <= 0

def isIntersect_ls(l, s):
    return cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < EPS

def isIntersect_cp(c, p):
    return abs(abs(c.p - p) - c.r) < EPS

def isIntersect_cl(c, l):
    return distance_lp(l, c.p) <= c.r + EPS

def isIntersect_cs(c, s):
    pass

def isIntersect_cc(c1, c2):
    pass


def distance_pp(p1, p2):
    return abs(p1-p2)

def distance_lp(l, p):
    return abs(projection(l,p)-p)

def distance_ll(l1, l2):
    return 0 if isIntersect_ll(l1, l2) else distance_lp(l1, l2.a)

def distance_sp(s, p):
    r = projection(s, p)
    if isIntersect_sp(s, r): return abs(r-p)
    return min(abs(s.a-p), abs(s.b-p))

def distance_ss(s1, s2):
    if isIntersect_ss(s1, s2): return 0
    return min([distance_sp(s1, s2.a), distance_sp(s1, s2.b), distance_sp(s2, s1.a), distance_sp(s2, s1.b)])

def distance_ls(l, s):
    if isIntersect_ls(l, s): return 0
    return min(distance_lp(l, s.a), distance_lp(l, s.b))


def crosspoint_ll(l1, l2):
    A = cross(l1.b - l1.a, l2.b - l2.a)
    B = cross(l1.b - l1.a, l1.b - l2.a)
    if eq(abs(A), 0) and eq(abs(B), 0): return l2.a
    return l2.a + (l2.b - l2.a) * B / A

def crosspoint_ss(s1, s2):
    return crosspoint_ll(s1, s2)

def crosspoint_lc(l, c):
    if eq(distance_lp(l, c.p), c.r): return [c.p]
    p = projection(l, c.p)
    e = (l.b - l.a) / abs(l.b-l.a)
    dis = (c.r**2-abs(p-c.p)**2)**0.5
    return [p + e*dis, p - e*dis]

def crosspoint_sc(s, c):
    pass

def crosspoint_cc(c1, c2):
    d = abs(c1.p-c2.p)
    if not abs(c1.r-c2.r) <= d <= c1.r+c2.r:
        return []
    mid_p = (c2.p * (c1.r**2-c2.r**2+d**2) + c1.p * (c2.r**2-c1.r**2+d**2)) / (2*d**2)
    tanvec = Rotation(c1.p-c2.p, pi/2)
    return crosspoint_lc(Line(mid_p, mid_p+tanvec), c1)


# pからのcの接点
def tangent_cp(c, p):
    return crosspoint_cc(c, Circle(p, (abs(p-c.p)**2 - c.r**2)**0.5))





import sys
input = sys.stdin.readline

def verify_1A():
    p1x, p1y, p2x, p2y = map(int, input().split())
    l = Line(Point(p1x, p1y), Point(p2x, p2y))
    Q = int(input())
    Query = [list(map(int, input().split())) for _ in range(Q)]
    for px, py in Query:
        p = Point(px, py)
        print(projection(l, p))

def verify_1B():
    p1x, p1y, p2x, p2y = map(int, input().split())
    l = Line(Point(p1x, p1y), Point(p2x, p2y))
    Q = int(input())
    Query = [list(map(int, input().split())) for _ in range(Q)]
    for px, py in Query:
        p = Point(px, py)
        print(reflection(l, p))

def verify_1C():
    p1x, p1y, p2x, p2y = map(int, input().split())
    p1 = Point(p1x, p1y); p2 = Point(p2x, p2y)
    Q = int(input())
    Query = [list(map(int, input().split())) for _ in range(Q)]
    for px, py in Query:
        p = Point(px, py)
        result = ccw(p1, p2, p)
        if result == 1:
            print("COUNTER_CLOCKWISE")
        elif result == -1:
            print("CLOCKWISE")
        elif result == 2:
            print("ONLINE_BACK")
        elif result == -2:
            print("ONLINE_FRONT")
        else:
            print("ON_SEGMENT")

def verify_2A():
    Q = int(input())
    Query = [list(map(int, input().split())) for _ in range(Q)]
    for p0x, p0y, p1x, p1y, p2x, p2y, p3x, p3y in Query:
        l1 = Line(Point(p0x, p0y), Point(p1x, p1y))
        l2 = Line(Point(p2x, p2y), Point(p3x, p3y))
        if isPararell(l1, l2):
            print(2)
        elif isVertical(l1, l2):
            print(1)
        else:
            print(0)

def verify_2B():
    Q = int(input())
    Query = [list(map(int, input().split())) for _ in range(Q)]
    for p0x, p0y, p1x, p1y, p2x, p2y, p3x, p3y in Query:
        s1 = Segment(Point(p0x, p0y), Point(p1x, p1y))
        s2 = Segment(Point(p2x, p2y), Point(p3x, p3y))
        if isIntersect_ss(s1, s2):
            print(1)
        else:
            print(0)
verify_2B()

Submission status: Accepted

Solution code:
def on_segment(u0,v0,u1,v1,u2,v2):
     return u1<=max(u0,u2) and u1>=min(u0,u2) and v1<=max(v0,v2) and v1>=min(v0,v2)

def signed_area(x0,y0,x1,y1):
    return (x0*y1-x1*y0)

q=int(input())

for _ in [0]*q:
    x0,y0,x1,y1,x2,y2,x3,y3=map(int,input().split())
    ta=signed_area(x1-x0,y1-y0,x2-x0,y2-y0)
    tb=signed_area(x1-x0,y1-y0,x3-x0,y3-y0)
    tc=signed_area(x3-x2,y3-y2,x0-x2,y0-y2)
    td=signed_area(x3-x2,y3-y2,x1-x2,y1-y2)

    """
    print(ta/2)
    print(tb/2)
    print(tc/2)
    print(td/2)
    
    print(on_segment(x0,y0,x2,y2,x1,y1))
    print(on_segment(x0,y0,x3,y3,x1,y1))
    print(on_segment(x2,y2,x0,y0,x3,y3))
    print(on_segment(x2,y2,x1,y1,x3,y3))
    """

    if ta*tb<0 and tc*td<0:
        print("1")
    elif ta==0 and on_segment(x0,y0,x2,y2,x1,y1):
        print("1")
    elif tb==0 and on_segment(x0,y0,x3,y3,x1,y1):
        print("1")
    elif tc==0 and on_segment(x2,y2,x0,y0,x3,y3):
        print("1")
    elif td==0 and on_segment(x2,y2,x1,y1,x3,y3):
        print("1")
    else:
        print("0")

Submission status: Accepted

Solution code:
# coding: utf-8
# Your code here!

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

EPS = 0.0000000001

class Point:
    
    global EPS
    
    def __init__(self, x = 0, y = 0):
        self.x = x
        self.y = y
        
        
    def __add__(a, b):
        s = a.x + b.x
        t = a.y + b.y
        return Point(s, t)
        
    def __sub__(a, b):
        s = a.x - b.x
        t = a.y - b.y
        return Point(s, t)
            
    def __mul__(self, a):
        s = a * self.x
        t = a * self.y
        return Point(s, t)
        
    def __truediv__(self, a):
        s = self.x / a
        t = self.y / a
        return Point(s, t)
            
            
            
            
    def norm(self):
        return self.x * self.x + self.y * self.y
        
    def abs(self):
        return self.norm() ** 0.5
            
    
            
            
    def __eq__(self, other):
        return abs(self.x - other.y) < self.EPS and abs(self.y - other.y) < self.EPS
            
            
            
    def dot(self, b):
        return self.x * b.x + self.y * b.y
        
    def cross(self, b):
        return self.x * b.y - self.y * b.x
    
    
class Segment:
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2


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

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

def intersectS(s1, s2):
    return intersect(s1.p1, s1.p2, s2.p1, s2.p2)



        
n = int(input())
for i in range(n):
    nums=list(map(int,input().split()))
    p1 = Point(nums[0], nums[1])
    p2 = Point(nums[2], nums[3])
    p3 = Point(nums[4], nums[5])
    p4 = Point(nums[6], nums[7])
    s1 = Segment(p1, p2)
    s2 = Segment(p3, p4)
    if intersectS(s1, s2):
        print(1)
    else:
        print(0)