def test_initial_status(self) -> None:
dsu = DSU(5)
for i, j in combinations(range(5), 2):
assert not dsu.same(i, j)
for index in range(5):
assert dsu.size(index) == 1
assert dsu.leader(index) == index
assert dsu.groups() == [[0], [1], [2], [3], [4]]
def resolve():
N = I()
f = LI_()
# 2 ** 連結成分数 - 1
dsu = DSU(N)
for i, e in enumerate(f):
dsu.merge(i, e)
lc_num = len(set(dsu.leader(i) for i in range(N)))
ans = pow(2, lc_num, MOD) - 1
print(ans)
def test_leader(self) -> None:
dsu = DSU(5)
dsu.merge(0, 1)
dsu.merge(0, 2)
assert dsu.leader(1) in [0, 1, 2]
assert dsu.leader(2) in [0, 1, 2]
assert dsu.leader(1) == dsu.leader(2)
assert dsu.leader(3) not in [0, 1, 2]
assert dsu.leader(4) not in [0, 1, 2]
# Test assertion of invalid indices
for i in (-1, 5):
with pytest.raises(AssertionError):
dsu.leader(i)