Expose conflict count via Solver::conflicts()

statistics() prints the cumulative conflict count but there was no
programmatic accessor for it. Add int64_t Solver::conflicts() mirroring
redundant()/irredundant(), reading internal->stats.conflicts. Valid in
both VALID and SOLVING state so it can be queried between solve() calls.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: msoos

src/cadical.hpp

@@ -686,6 +686,15 @@ class Solver {
   int64_t redundant () const;   // Number of active redundant clauses.
   int64_t irredundant () const; // Number of active irredundant clauses.
 
+  // Cumulative number of conflicts generated during search, as also
+  // reported by 'statistics ()'.  Valid both in 'VALID' and 'SOLVING'
+  // state so it can be queried after (or between) 'solve' calls.
+  //
+  //   require (VALID | SOLVING)
+  //   ensure (VALID | SOLVING)
+  //
+  int64_t conflicts () const;
+
   //------------------------------------------------------------------------
   // This function executes the given number of preprocessing rounds. It is
   // similar to 'solve' with 'limits ("preprocessing", rounds)' except that

src/solver.cpp

@@ -1068,6 +1068,14 @@ int64_t Solver::irredundant () const {
   return res;
 }
 
+int64_t Solver::conflicts () const {
+  TRACE ("conflicts");
+  REQUIRE_VALID_OR_SOLVING_STATE ();
+  int64_t res = internal->stats.conflicts;
+  LOG_API_CALL_RETURNS ("conflicts", res);
+  return res;
+}
+
 /*------------------------------------------------------------------------*/
 
 void Solver::freeze (int lit) {