1 files changed, 115 insertions, 0 deletions
diff --git a/ai.cpp b/ai.cpp
new file mode 100644
index 0000000..bef4567
--- /dev/null
+++ b/ai.cpp
@@ -0,0 +1,115 @@
+#include <stdlib.h>
+#include <time.h>
+
+#include "ai.hpp"
+#include "GameField.hpp"
+
+enum scores {
+	MIN_SCORE = -1000,
+	MAX_SCORE = 1000,
+	NONE_SCORE = 0,
+	DRAW_SCORE = 2,
+	WIN_SCORE = 10,
+	LOSE_SCORE = -10
+};
+
+AI::AI(int d) : max_depth(d)
+{
+	srand(time(NULL));
+}
+
+void AI::GetFirstMove(int &my, int &mx, int rows, int cols)
+{
+	my = rand() % rows;
+	mx = rand() % cols;
+}
+
+void AI::GetBestMove(int &my, int &mx, GameField field)
+{
+	int score = MIN_SCORE;
+	int rows = field.GetRows();
+	int cols = field.GetCols();
+
+	int y, x;
+	for(y = 0; y < rows; y++) {
+		for(x = 0; x < cols; x++)
+		{
+			if(!field.CanMove(y, x))
+				continue;
+			field.Move(y, x);
+			int result = min(field, 1); // min because next move by player
+			field.UndoMove(y, x);
+			if(result > score) {
+				score = result;
+				my = y;
+				mx = x;
+			}
+		}
+	}
+}
+
+int AI::score(GameField field)
+{
+	int state = field.GetState();
+	if(state == G_DRAW)
+		return DRAW_SCORE;
+	if(state == G_XPLAYER)
+		return field.GetWhoMove() == G_XPLAYER ? WIN_SCORE : LOSE_SCORE;
+	if(state == G_OPLAYER)
+		return field.GetWhoMove() == G_OPLAYER ? WIN_SCORE : LOSE_SCORE;
+	return NONE_SCORE;
+}
+
+int AI::min(GameField field, int depth)
+{
+	if(field.GetState() != G_NONE || depth >= max_depth) {
+		return score(field);
+	}
+
+	int score = MAX_SCORE;
+	int rows = field.GetRows();
+	int cols = field.GetCols();
+
+	int y, x;
+	for(y = 0; y < rows; y++) {
+		for(x = 0; x < cols; x++)
+		{
+			if(!field.CanMove(y, x))
+				continue;
+			field.Move(y, x);
+			int result = max(field, depth + 1);
+			field.UndoMove(y, x);
+			if(result < score)
+				score = result;
+		}
+	}
+
+	return score;
+}
+
+int AI::max(GameField field, int depth)
+{
+	if(field.GetState() != G_NONE || depth >= max_depth) {
+		return score(field);
+	}
+
+	int score = MIN_SCORE;
+	int rows = field.GetRows();
+	int cols = field.GetCols();
+
+	int y, x;
+	for(y = 0; y < rows; y++) {
+		for(x = 0; x < cols; x++)
+		{
+			if(!field.CanMove(y, x))
+				continue;
+			field.Move(y, x);
+			int result = max(field, depth + 1);
+			field.UndoMove(y, x);
+			if(result > score)
+				score = result;
+		}
+	}
+
+	return score;
+}