Esempio n. 1
0
        /// <summary>
        /// Computes the distances to the goals for the specified pattern.
        /// </summary>
        /// <param name="pattern">Pattern (i.e. variables of the pattern) to process.</param>
        private PatternValuesDistances ComputePatternDistances(int[] pattern)
        {
            IHeap <double, ISimpleConditions> fringe = new LeftistHeap <ISimpleConditions>();

            InsertPatternConditions(fringe, (Conditions)Problem.GoalConditions, 0, pattern);

            PatternValuesDistances patternValuesDistances = new PatternValuesDistances();

            while (fringe.GetSize() > 0)
            {
                double            distance   = fringe.GetMinKey();
                ISimpleConditions conditions = fringe.RemoveMin();

                int[] patternValues = conditions.GetAssignedValues();

                Debug.Assert(pattern.Length == conditions.GetSize());
                Debug.Assert(pattern.Length == patternValues.Length);

                if (patternValuesDistances.ContainsKey(patternValues))
                {
                    // already processed with a lower cost
                    continue;
                }

                patternValuesDistances.Add(patternValues, distance);

                foreach (var predecessor in Problem.GetPredecessors(conditions))
                {
                    IConditions predecessorConditions = (IConditions)predecessor.GetPredecessorConditions();
                    IOperator   predecessorOperator   = (IOperator)predecessor.GetAppliedOperator();

                    foreach (var predecessorSimpleConditions in predecessorConditions.GetSimpleConditions())
                    {
                        double cost = distance + predecessorOperator.GetCost();
                        InsertPatternConditions(fringe, predecessorSimpleConditions, cost, pattern);
                    }
                }
            }

            return(patternValuesDistances);
        }