ai: 增加空着向前裁剪部分代码 (未完成)

宏未开启。

include/config.h

@@ -57,6 +57,8 @@
 #define DEPTH_ADJUST (0)
 //#define FIX_DEPTH   (24)
 
+//#define NULL_MOVE
+
 //#define FIRST_MOVE_STAR_PREFERRED
 
 //#define TIME_STAT

src/ai/movegen.cpp

@@ -172,6 +172,13 @@ int StateInfo::generateMoves(Stack<move_t, MOVE_COUNT> &moves)
     return moves.size();
 }
 
+int StateInfo::generateNullMove(Stack<move_t, MOVE_COUNT> &moves)
+{
+    moves.clear();
+    moves.push_back((move_t)SQ_0);
+    return moves.size();
+}
+
 void MoveList::create()
 {
     // Note: 未严格按 direction_t 中枚举的顺序从左到右排列

src/ai/search.cpp

@@ -799,6 +799,20 @@ value_t AIAlgorithm::search(depth_t depth, value_t alpha, value_t beta, Node *no
         }
 #endif
 
+#ifdef NULL_MOVE
+        // 空着向前裁剪 (WIP)
+        doNullMove();
+        st->generateNullMove(moves);
+        st->generateChildren(moves, this, node);
+        value = -search(depth - 1 - 2, -beta, -beta + 1, node->children[0]);
+        undoNullMove();
+
+        if (value >= beta) {
+            node->value = beta;
+            return beta;
+        }
+#endif
+
 #ifdef TRANSPOSITION_TABLE_ENABLE
         // 记录确切的哈希值
         TT::recordHash(node->value,
@@ -963,6 +977,18 @@ void AIAlgorithm::undoMove()
     positionStack.pop();
 }
 
+void AIAlgorithm::doNullMove()
+{
+    // 执行空着
+    st->doNullMove();
+}
+
+void AIAlgorithm::undoNullMove()
+{
+    // 执行空着
+    st->undoNullMove();
+}
+
 #ifdef ALPHABETA_AI
 const char* AIAlgorithm::bestMove()
 {

src/ai/search.h

@@ -190,6 +190,9 @@ public:
     // 撤销着法
     void undoMove();
 
+    void doNullMove();
+    void undoNullMove();
+
 #ifdef TRANSPOSITION_TABLE_ENABLE
     // 清空哈希表
     void clearTT();

src/game/position.cpp

@@ -1051,6 +1051,18 @@ void StateInfo::changeSideToMove()
     setSideToMove(Player::getOpponent(position->sideToMove));
 }
 
+bool StateInfo::doNullMove()
+{
+    changeSideToMove();
+    return true;
+}
+
+bool StateInfo::undoNullMove()
+{
+    changeSideToMove();
+    return true;
+}
+
 void StateInfo::setTips()
 {
     string winnerStr, t;

src/game/position.h

@@ -249,6 +249,10 @@ public:
 
     // 着法生成
     int generateMoves(Stack<move_t, MOVE_COUNT> &moves);
+    int generateNullMove(Stack<move_t, MOVE_COUNT> &moves);
+
+    bool doNullMove();
+    bool undoNullMove();
 
     // 判断胜负
     player_t getWinner() const;