// Propagate the last node in _nodes_to_propagate. This means applying all the constraints in its clusters. Returns false if we get a conflict from this propagation
private bool Propagate()
{
int node_idx_to_propagate = UTL.ExtractBack(ref _nodes_to_propagate);
if (_nodes[node_idx_to_propagate].is_propagated)
{
return(true); // the node has already been propagated. Shouldn't happen
}
bool legal_propagation = true;
if (_nodes[node_idx_to_propagate].is_true)
{
foreach (int neighbour_idx in _nodes[node_idx_to_propagate].neighbour_ids)
{
if (!GiveValueToNode(neighbour_idx, false))
{
legal_propagation = false;
}
}
}
foreach (int cluster_idx in _nodes[node_idx_to_propagate].cluster_ids)
{
if (!GiveNodeValueToCluster(ref _clusters[cluster_idx], _nodes[node_idx_to_propagate].is_true))
{
legal_propagation = false;
}
}
_nodes[node_idx_to_propagate].is_propagated = true;
++_num_fixed_nodes_propagated;
return(legal_propagation);
}
// removes the last Guess, since it proved to be wrong
private void RemoveLastGuess()
{
if (_guess_list.Count == 0)
{
return; // this should never happen
}
for (int node_idx = 0; node_idx < Volume; ++node_idx)
{
if (_nodes[node_idx].time == NumGuesses())
{
FreeNode(node_idx);
}
;
}
int last_guessed_node = UTL.ExtractBack(ref _guess_list);
GiveValueToNode(last_guessed_node, false);
_nodes_to_propagate = new List <int> {
last_guessed_node
};
}