update

Search.cpp

@@ -1,8 +1,11 @@
+#include <iostream>
 #include "Search.hpp"
 #include "Move.hpp"
 #include "Board.hpp"
 
-int Search::search(Node *node, const Board &board, unsigned depth) {
+#include <algorithm>
+
+int Search::search(Node *node, const Board &board, unsigned depth, int alpha, int beta) {
 
     if (depth == 0) {
         return evaluate(board);
@@ -13,6 +16,7 @@ int Search::search(Node *node, const Board &board, unsigned depth) {
     if (moves.empty()) {
         return evaluate(board);
     }
+    std::stable_sort(moves.begin(), moves.end());
 
     int maxValue = kNegInfinity;
     for (auto &kMove: moves) {
@@ -20,13 +24,18 @@ int Search::search(Node *node, const Board &board, unsigned depth) {
         nodeBoard.makeMove(kMove);
 
         Node child(kMove);
-        child.value = search(&child, nodeBoard, depth - 1);
+        child.value = search(&child, nodeBoard, depth - 1, -beta, -alpha);
 
         auto value = -child.value;
         if (value > maxValue) {
             maxValue = value;
             node->next = std::make_unique<Node>(child);
         }
+
+        alpha = std::max(alpha, value);
+        if (alpha >= beta) {
+            break;
+        }
     }
 
     node->value = maxValue;
@@ -39,9 +48,11 @@ int Search::evaluate(const Board &board) {
     return board.evaluate();
 }
 
+
 PrincipalVariation Search::start(const Board &board) {
     auto rootMoves = Board::MoveVec();
     board.pseudoLegalMoves(rootMoves);
+    std::stable_sort(rootMoves.begin(), rootMoves.end());
 
     if (rootMoves.size() <= 1) {
         auto b = board;
@@ -56,7 +67,7 @@ PrincipalVariation Search::start(const Board &board) {
         Board nodeBoard = board;
         nodeBoard.makeMove(kMove);
 
-        auto value = -search(&node, nodeBoard, 4);
+        auto value = -search(&node, nodeBoard, 5, kNegInfinity, kPosInfinity);
         if (value > best->value) {
             best->child = std::make_unique<Node>(node);
             best->board = nodeBoard;