def test_solve_square(self):
"""Solve problem with square
start ---1--> A
| |
1 1
| |
V V
B ---1--> finish
Right answer is (1*1 + 1*1)
"""
start = Vertex('start')
finish = Vertex('finish')
a = Vertex('a')
b = Vertex('b')
for S in semirings:
start_a = Edge(start, a, S.unity())
start_b = Edge(start, b, S.unity())
a_finish = Edge(a, finish, S.unity())
b_finish = Edge(b, finish, S.unity())
g = DynamicProgramming([start, a, b, finish], [start_a, start_b,
a_finish, b_finish])
g.set_start(start)
g.set_finish(finish)
self.assertEqual(g.solve(S), S.unity()+S.unity())
def test_solve_simple(self):
"""Solve simple problem
start --1--> finish
Right answer is 1
"""
start = Vertex('start')
finish = Vertex('finish')
for S in semirings:
e = Edge(start, finish, S.unity())
g = DynamicProgramming([start, finish], [e])
g.set_start(start)
g.set_finish(finish)
self.assertEqual(g.solve(S), S.unity())
def test_solve_crossed_square(self):
"""Find length of the shortest path (min,+)
start -5-> A ---1----> B --3--> C
| | |
1 0 9
| | |
V V V
x --5--> y --2--> z --1--> finish
Right answer is 8
"""
start = Vertex('start')
finish = Vertex('finish')
a = Vertex('a')
b = Vertex('b')
c = Vertex('c')
x = Vertex('x')
y = Vertex('y')
z = Vertex('z')
start_a = Edge(start, a, SemiringMinPlusElement(5))
a_b = Edge(a, b, SemiringMinPlusElement(1))
b_c = Edge(b, c, SemiringMinPlusElement(3))
c_finish = Edge(c, finish, SemiringMinPlusElement(9))
start_x = Edge(start, x, SemiringMinPlusElement(1))
x_y = Edge(x, y, SemiringMinPlusElement(5))
y_z = Edge(y, z, SemiringMinPlusElement(2))
z_finish = Edge(z, finish, SemiringMinPlusElement(1))
a_y = Edge(a, y, SemiringMinPlusElement(0))
g = DynamicProgramming([start, finish, a, b, c, x, y, z],
[start_a, a_b, b_c, c_finish,
start_x, x_y, y_z, z_finish,
a_y])
g.set_start(start)
g.set_finish(finish)
self.assertEqual(g.solve(SemiringMinPlusElement),
SemiringMinPlusElement(8))