got through stack backward only until the first useful

src/nfa/nfa.cc

@@ -20,6 +20,7 @@
 #include <optional>
 #include <unordered_set>
 #include <iterator>
+#include <ranges>
 
 // MATA headers
 #include "mata/utils/sparse-set.hh"
@@ -329,7 +330,11 @@ BoolVector Nfa::get_useful_states(bool stop_at_first_useful_state) const {
                 // propagate usefulness to the closed SCC
                 for(const State& st : scc) useful[st] = true;
                 // propagate usefulness to predecessors in @p tarjan_stack
-                for(const State& st : tarjan_stack) useful[st] = true;
+                for(const State& st :std::views::reverse(tarjan_stack)) {
+                    if (useful[st])
+                        break;
+                    useful[st] = true;
+                }
             }
         }
         // all successors have been processed, we can remove act_state from the program stack