def bfs(graph, root):
"""Return vertices of a component of graph in some bfs order, starting with root."""
done = 0
front = root
while front:
v = first(front)
yield v
done |= v
front |= graph.neighborhoods[v]
front = subtract(front, done)
def incremental_un_heuristic(G):
lboolw_components = []
decomposition_components = []
for component in components(G):
best_lboolw = Infinity
best_decomposition = None
for i, start in enumerate([first(component)]):
#for i, start in enumerate(iterate(component)):
print('{}th starting vertex'.format(i))
right = subtract(component, start)
left = start
un_left = increment_un(G, 0, {0}, start)
booldim_left = 1
decomposition = [start]
lboolw = len(un_left)
for _ in range(size(component) - 1):
best_vertex, best_un, _ = greedy_step(G, left, right, un_left,
booldim_left, {}, Infinity)
booldim_left = len(best_un)
lboolw = max(lboolw, booldim_left)
un_left = best_un
decomposition.append(best_vertex)
right = subtract(right, best_vertex)
left = left | best_vertex
if lboolw < best_lboolw:
best_lboolw = lboolw
best_decomposition = decomposition
lboolw_components.append(best_lboolw)
decomposition_components.append(best_decomposition)
total_lboolw = max(lboolw_components)
total_decomposition = [v for part in decomposition_components for v in part]
return total_lboolw, total_decomposition
