def any_segments_intersect(S):
'''This algorithm takes as input a set S of n line segments, returning the boolean value TRUE if any pair of segments in S intersects, and FALSE otherwise.'''
T = rb_tree()
segment_list = []
point_list = []
for s in S:
segment_list.append(segment(s))
for s in segment_list:
point_list.append(point([s[0][0], 0, s[0][1]], s))
point_list.append(point([s[1][0], 1, s[1][1]], s))
heap_point = max_heap(point_list)
heap_point.heapsort()
for p in heap_point:
if p[1] == 0:
s = p.segment
T.insert(s)
a = T.above(s)
b = T.below(s)
if (a != None and segments_intersect(a[0], a[1], s[0], s[1])) or (b != None and segments_intersect(b[0], b[1], s[0], s[1])):
return True
if p[1] == 1:
s = p.segment
a = T.above(s)
b = T.below(s)
# print( a)
# print( b)
# print( type(a))
# print( type(b))
if a != None and b != None and segments_intersect(a[0], a[1], b[0], b[1]):
return True
T.delete(s)
return False
def any_segments_intersect(S):
'''This algorithm takes as input a set S of n line segments, returning the boolean value TRUE if any pair of segments in S intersects, and FALSE otherwise.'''
T = rb_tree()
segment_list = []
point_list = []
for s in S:
segment_list.append(segment(s))
for s in segment_list:
point_list.append(point([s[0][0], 0, s[0][1]], s))
point_list.append(point([s[1][0], 1, s[1][1]], s))
heap_point = max_heap(point_list)
heap_point.heapsort()
for p in heap_point:
if p[1] == 0:
s = p.segment
T.insert(s)
a = T.above(s)
b = T.below(s)
if (a != None and segments_intersect(a[0], a[1], s[0], s[1])) or (b != None and segments_intersect(b[0], b[1], s[0], s[1])):
return True
if p[1] == 1:
s = p.segment
a = T.above(s)
b = T.below(s)
# print a
# print b
# print type(a)
# print type(b)
if a != None and b != None and segments_intersect(a[0], a[1], b[0], b[1]):
return True
T.delete(s)
return False
def right_horizontal_ray_intersect(p0, p1, p2):
'''An algorithm to determine whether a given right horizontal ray from p0 intersects a line segment p1p2'''
max_x = max(p1[0], p2[0])
if max_x < p0[0]:
return False
# When max(x1, x2) = x0, if intersecting, the intersection point must be po, then po must be on the line segment p1p2
elif max_x == p0[1]:
if p1[0] == p2[0] and min(p1[1], p2[1]) <= p0[1] and max(p1[1], p2[1]) >= p0[1]:
return True
else:
return equal(p0, p1) or equal(p0, p2)
else:
return segments_intersect(p1, p2, p0, (max_x, p0[1]))
def right_horizontal_ray_intersect(p0, p1, p2):
'''An algorithm to determine whether a given right horizontal ray from p0 intersects a line segment p1p2'''
max_x = max(p1[0], p2[0])
if max_x < p0[0]:
return False
# When max(x1, x2) = x0, if intersecting, the intersection point must be po, then po must be on the line segment p1p2
elif max_x == p0[1]:
if p1[0] == p2[0] and min(p1[1], p2[1]) <= p0[1] and max(
p1[1], p2[1]) >= p0[1]:
return True
else:
return equal(p0, p1) or equal(p0, p2)
else:
return segments_intersect(p1, p2, p0, (max_x, p0[1]))
