def test_usage():
g = MinCostFlow(2)
g.add_edge(0, 1, 1, 2)
assert [1, 2] == g.flow(0, 1)
g = MinCostFlow(2)
g.add_edge(0, 1, 1, 2)
assert [[0, 0], [1, 2]] == g.slope(0, 1)
def test_stress():
for phase in range(1000):
n = randint(2, 20)
m = randint(1, 100)
s, t = randpair(0, n - 1)
if randint(0, 1):
s, t = t, s
g_mf = MaxFlow(n)
g = MinCostFlow(n)
for i in range(m):
u = randint(0, n - 1)
v = randint(0, n - 1)
cap = randint(0, 10)
cost = randint(0, 10000)
g.add_edge(u, v, cap, cost)
g_mf.add_edge(u, v, cap)
flow, cost = g.flow(s, t)
assert g_mf.flow(s, t) == flow
cost2 = 0
v_cap = [0] * n
for from_, to, _, flow_e, cost_e in g.edges():
v_cap[from_] -= flow_e
v_cap[to] += flow_e
cost2 += flow_e * cost_e
assert cost == cost2
for i in range(n):
if i == s:
assert -flow == v_cap[i]
elif i == t:
assert flow == v_cap[i]
else:
assert 0 == v_cap[i]
# check: there is no negative-cycle
dist = [0] * n
while True:
update = False
for from_, to, cap, flow_e, cost_e in g.edges():
if flow_e < cap:
ndist = dist[from_] + cost_e
if ndist < dist[to]:
update = True
dist[to] = ndist
if flow_e:
ndist = dist[to] - cost_e
if ndist < dist[from_]:
update = True
dist[from_] = ndist
if not update:
break
def test_zero():
g1 = MinCostFlow()
g2 = MinCostFlow(0)
def test_invalid(p):
g = MinCostFlow(2)
# https://github.com/atcoder/ac-library/issues/51
with pytest.raises(AssertionError) as e:
g.add_edge(*p)
def test_samecostpaths():
g = MinCostFlow(3)
assert 0 == g.add_edge(0, 1, 1, 1)
assert 1 == g.add_edge(1, 2, 1, 0)
assert 2 == g.add_edge(0, 2, 2, 1)
assert [[0, 0], [3, 3]] == g.slope(0, 2)
def test_selfloop():
g = MinCostFlow(3)
assert 0 == g.add_edge(0, 0, 100, 123)
assert [0, 0, 100, 0, 123] == g.get_edge(0)
def test_assign(p):
g = MinCostFlow()
s, t = p
with pytest.raises(AssertionError) as e:
g.slope(s, t)
def test_simple():
g = MinCostFlow(4)
g.add_edge(0, 1, 1, 1)
g.add_edge(0, 2, 1, 1)
g.add_edge(1, 3, 1, 1)
g.add_edge(2, 3, 1, 1)
g.add_edge(1, 2, 1, 1)
expect = [[0, 0], [2, 4]]
assert expect == g.slope(0, 3, 10)
assert g.get_edge(0) == [0, 1, 1, 1, 1]
assert g.get_edge(1) == [0, 2, 1, 1, 1]
assert g.get_edge(2) == [1, 3, 1, 1, 1]
assert g.get_edge(3) == [2, 3, 1, 1, 1]
assert g.get_edge(4) == [1, 2, 1, 0, 1]