private ValuedMove AlphaBetaMove(GameState state, AlphaBetaTreeNode node, int alpha, int beta)
        {
            if (state.IsFinal)
                return state.Leaf(Evaluate(state, false), node);

            ValuedMove curr = new ValuedMove(Int32.MinValue);
            foreach (var pos in state.Grid.FreeGrid)
            {
                AlphaBetaTreeNode newNode = node == null ? null : node.AddChild("Put in " + pos);
                ValuedMove minCheck = AlphaBetaPick(state.Move(pos), newNode, alpha, beta);
                curr.CheckSmaller(minCheck, pos);
                if (curr.BetaPrune(beta, node)) return curr;
                if (curr.Value == 1000) return curr;
                alpha = Math.Max(alpha, curr.Value);
            }

            if (node != null) node.Value = curr.Value.ToString();
            return curr;
        }