implement discarding dupes and sacrifice discards

include/game_state.hpp

@@ -194,7 +194,7 @@ namespace Hanabi
 
     _actions_log.emplace(ActionType::play, played_card, index, _num_clues == 8, strike);
 
-    if (is_playable(played_card))
+    if (!strike)
     {
       --_stacks[played_card.suit];
       _score++;
@@ -951,10 +951,62 @@ namespace Hanabi
     // Check for discards now
     if (_pace > 0 and _num_clues < max_num_clues)
     {
-      for (std::uint8_t index = 0; index < hand_size; index++)
+      // This will hold the index of trash to discard
+      std::uint8_t const invalid_index = std::numeric_limits<std::uint8_t>::max();
+      std::uint8_t discard_index = invalid_index;
+
+      for (hand_index_t index = 0; index < hand_size; index++)
       {
         if (is_trash(hand[index]))
         {
+          discard_index = index;
+
+          // All discards are equivalent, do not continue searching for different trash
+          break;
+        }
+      }
+
+      // If no trivial trash found, check for duplicates next
+      if (discard_index == invalid_index) {
+        for (std::uint8_t index = 0; index < hand_size; index++) {
+          Card const card = _hands[_turn][index];
+          auto it = std::find_if(_hands[_turn].begin() + index + 1, _hands[_turn].end(), [&card, this](Card const & card_in_hand) {
+            return card_in_hand == card;
+          });
+          if (it != _hands[_turn].end()) {
+            // found a duplicate to discard
+            discard_index = index;
+            // Since we are discarding essentially trash, we do not have to consider further actions
+            break;
+          }
+        }
+      }
+
+      // Discard if we found trash now
+      if (discard_index != invalid_index) {
+        probability_t sum_of_probabilities = 0;
+
+        do_for_each_potential_draw(discard_index, false, [this, &sum_of_probabilities](const unsigned long multiplicity) {
+          sum_of_probabilities += evaluate_state() * multiplicity;
+        });
+
+        const unsigned long total_weight = std::max(static_cast<unsigned long>(_weighted_draw_pile_size), 1ul);
+        const probability_t probability_discard = sum_of_probabilities / total_weight;
+        best_probability = std::max(best_probability, probability_discard);
+
+        best_probability = std::max(best_probability, probability_discard);
+        if (best_probability == 1)
+        {
+          update_tablebase(id_of_state, best_probability);
+          return best_probability;
+        };
+      } else {
+        // If we reach this state, then there are no dupes in hand, so we need to check if we want to
+        // sacrifice cards in hand
+        for(hand_index_t index = 0; index < hand_size; ++index) {
+          if(!is_critical(hand[index])) {
+            std::cout << "Considered sacrificing card " << hand[index] << "in the following state:\n" << *this << std::endl;
+            // consider discarding this
             probability_t sum_of_probabilities = 0;
 
             do_for_each_potential_draw(index, false, [this, &sum_of_probabilities](const unsigned long multiplicity) {
@@ -971,9 +1023,7 @@ namespace Hanabi
               update_tablebase(id_of_state, best_probability);
               return best_probability;
             };
-
-          // All discards are equivalent, do not continue searching for different trash
-          break;
+          }
         }
       }
     }