def test_no_edges():
edges = np.empty((0, 2), dtype=np.int32)
result = fast_dfs(3, edges)
assert np.allclose(result.dfs_edges, [[0, 1], [0, 2]])
assert result.was_disconnected
assert not result.had_cycles
assert not result.was_tree
def test_disconnected_with_cycles():
vert_num = 6
edges = np.array([[0, 1], [1, 2], [0, 2], [5, 4], [4, 3], [3, 5]])
expected_dfs_edges = np.array([[0, 1], [1, 2], [0, 3], [3, 4], [4, 5]])
result = fast_dfs(vert_num, edges)
assert np.allclose(result.dfs_edges, expected_dfs_edges)
assert result.was_disconnected
assert result.had_cycles
assert not result.was_tree
def test_long_path():
n = 10000
ends = np.cumsum(np.ones(n - 1), dtype=np.int32)
starts = ends - 1
edges = np.array([starts, ends]).T
result = fast_dfs(n, edges)
assert np.allclose(result.dfs_edges, edges)
assert not result.was_disconnected
assert not result.had_cycles
assert result.was_tree
def test_connected_with_cycles():
vert_num = 20
graph = nx.generators.wheel_graph(vert_num)
edges = np.array(list(graph.edges()), dtype=np.int32)
expected_dfs_edges = _dfs_with_networkx(vert_num, edges)
result = fast_dfs(vert_num, edges)
assert np.allclose(result.dfs_edges, expected_dfs_edges)
assert not result.was_disconnected
assert result.had_cycles
assert not result.was_tree
def test_forest():
vert_num = 10
edges = np.array([[3, 4], [4, 8], [0, 4], [9, 0], [2, 7], [5, 1], [1, 6]])
expected_dfs_edges = np.array([[0, 4], [4, 3], [4, 8], [0, 9], [0, 1],
[1, 5], [1, 6], [0, 2], [2, 7]])
result = fast_dfs(vert_num, edges)
assert np.allclose(result.dfs_edges, expected_dfs_edges)
assert result.was_disconnected
assert not result.had_cycles
assert not result.was_tree
def test_tree():
vert_num = 1000
graph = nx.generators.trees.random_tree(vert_num, seed=0)
edges = np.array(list(graph.edges()), dtype=np.int32)
expected_dfs_edges = _dfs_with_networkx(vert_num, edges)
result = fast_dfs(vert_num, edges)
assert np.allclose(result.dfs_edges, expected_dfs_edges)
assert not result.was_disconnected
assert not result.had_cycles
assert result.was_tree