void LpSolveInterface::GraphParsingState::SetObjectiveFunction(lprec* model) {
set_minim(CHECK_NOTNULL(model));
int num_x_vars = edge_to_crossing_variable_indices_.size();
unique_ptr<int[]> indices(new int[num_x_vars]);
unique_ptr<REAL[]> coeffs(new REAL[num_x_vars]);
int added = 0;
for (const pair<int, int>& e : edge_to_crossing_variable_indices_) {
indices[added] = e.second;
Edge* edge = graph_->internal_edges().at(e.first);
coeffs[added++] = (REAL)(edge->Weight());
}
set_obj_fnex(model, num_x_vars, coeffs.get(), indices.get());
}
int Edge::compareTo(Edge that){
if(this->Weight() < that.Weight()) return 1;
else if(this->Weight() > that.Weight()) return -1;
else return 0;
}