SCCDecomposition: Fixed topological sort of SCCs connected via '0'-valued transitions

src/storm/storage/StronglyConnectedComponentDecomposition.cpp

@@ -324,12 +324,14 @@ namespace storm {
                             successorSCCs.clear();
                             for (auto const& state : currentScc) {
                                 for (auto const& entry : transitions.getRowGroup(state)) {
+                                    if (!storm::utility::isZero(entry.getValue())) {
                                         auto const& successorSCC = sccIndices[entry.getColumn()];
                                         if (successorSCC != currentSccIndex && unsortedSCCs.get(successorSCC)) {
                                             successorSCCs.insert(successorSCC);
                                         }
                                     }
                                 }
+                            }
                             sccStack.insert(sccStack.end(), successorSCCs.begin(), successorSCCs.end());
                             
                         }
@@ -345,12 +347,14 @@ namespace storm {
                             uint32_t& currentChainSize = chainSizes[currentSccIndex];
                             for (auto const& state : scc) {
                                 for (auto const& entry : transitions.getRowGroup(state)) {
+                                    if (!storm::utility::isZero(entry.getValue())) {
                                         auto const& successorSCC = sccIndices[entry.getColumn()];
                                         if (successorSCC != currentSccIndex) {
                                             currentChainSize = std::max(currentChainSize, chainSizes[successorSCC] + 1);
                                         }
                                     }
                                 }
+                            }
                             *longestChainSize = std::max<uint64_t>(*longestChainSize, currentChainSize);
                         }