/// <summary>
/// Obtém uma solução a partir duma aproximação inicial.
/// </summary>
/// <param name="approximateMedians">As medianas.</param>
/// <param name="costs">Os custos.</param>
/// <param name="niter">O número máximo melhoramentos a serem aplicados à solução encontrada.</param>
/// <returns>A solução construída a partir da aproximação.</returns>
public GreedyAlgSolution <CoeffType> Run(
CoeffType[] approximateMedians,
ILongSparseMathMatrix <CoeffType> costs,
int niter)
{
if (approximateMedians == null)
{
throw new ArgumentNullException("approximateMedians");
}
else if (costs == null)
{
throw new ArgumentNullException("costs");
}
else if (approximateMedians.Length != costs.GetLength(1))
{
throw new ArgumentException("The number of medians must match the number of columns in costs matrix.");
}
else
{
var settedSolutions = new IntegerSequence();
var approximateSolutions = new List <int>();
var sum = this.coeffsField.AdditiveUnity;
for (int i = 0; i < approximateMedians.Length; ++i)
{
var currentMedian = approximateMedians[i];
if (!this.coeffsField.IsAdditiveUnity(currentMedian))
{
sum = this.coeffsField.Add(sum, approximateMedians[i]);
if (this.converter.CanApplyDirectConversion(currentMedian))
{
var converted = this.converter.DirectConversion(currentMedian);
if (converted == 1)
{
settedSolutions.Add(i);
}
else
{
throw new OdmpProblemException(string.Format(
"The median {0} at position {1} of medians array can't be converted to the unity.",
currentMedian,
i));
}
}
else
{
approximateSolutions.Add(i);
}
}
}
if (this.converter.CanApplyDirectConversion(sum))
{
var convertedSum = this.converter.DirectConversion(sum);
if (convertedSum <= 0 || convertedSum > approximateMedians.Length)
{
throw new IndexOutOfRangeException(string.Format(
"The medians sum {0} is out of bounds. It must be between 1 and the number of elements in medians array.",
convertedSum));
}
var solutionBoard = new CoeffType[approximateMedians.Length];
var marked = new BitArray(approximateMedians.Length, false);
if (settedSolutions.Count == convertedSum)
{
var result = new GreedyAlgSolution <CoeffType>(settedSolutions);
result.Cost = this.ComputeCost(settedSolutions, costs, solutionBoard, marked);
return(result);
}
else
{
// Partição das mediana em dois conjuntos: as que vão falzer parte da solução e as restantes
// entre as soluções aproximadas.
var recoveredMedians = new List <int>();
var unrecoveredMedians = new List <int>();
var innerComparer = new InnerComparer(approximateMedians, this.comparer);
approximateSolutions.Sort(innerComparer);
var count = convertedSum - settedSolutions.Count;
var i = 0;
for (; i < count; ++i)
{
recoveredMedians.Add(approximateSolutions[i]);
settedSolutions.Add(approximateSolutions[i]);
}
for (; i < approximateSolutions.Count; ++i)
{
unrecoveredMedians.Add(approximateSolutions[i]);
}
var currentCost = this.ComputeCost(settedSolutions, costs, solutionBoard, marked);
// Processa as melhorias de uma forma simples caso seja possível
if (unrecoveredMedians.Count > 0 && niter > 0)
{
var exchangeSolutionBoard = new CoeffType[solutionBoard.Length];
var currentBestBoard = new CoeffType[solutionBoard.Length];
for (i = 0; i < niter; ++i)
{
var itemToExchange = -1;
var itemToExchangeIndex = -1;
var itemToExchangeWith = -1;
var itemToExchangeWithIndex = -1;
var minimumCost = this.coeffsField.AdditiveUnity;
for (int j = 0; j < recoveredMedians.Count; ++j)
{
for (int k = 0; k < unrecoveredMedians.Count; ++k)
{
var replacementCost = this.ComputeReplacementCost(
unrecoveredMedians[k],
recoveredMedians[j],
settedSolutions,
costs,
solutionBoard,
exchangeSolutionBoard);
if (this.comparer.Compare(replacementCost, minimumCost) < 0)
{
// Aceita a troca
itemToExchange = recoveredMedians[j];
itemToExchangeIndex = j;
itemToExchangeWith = unrecoveredMedians[k];
itemToExchangeWithIndex = k;
minimumCost = replacementCost;
var swapBestBoard = currentBestBoard;
currentBestBoard = exchangeSolutionBoard;
exchangeSolutionBoard = swapBestBoard;
}
}
}
if (itemToExchange == -1 || itemToExchangeWith == -1)
{
i = niter - 1;
}
else
{
// Efectua a troca
var swapSolutionBoard = solutionBoard;
solutionBoard = currentBestBoard;
currentBestBoard = swapSolutionBoard;
currentCost = this.coeffsField.Add(currentCost, minimumCost);
settedSolutions.Remove(itemToExchange);
settedSolutions.Add(itemToExchangeWith);
var swap = recoveredMedians[itemToExchangeIndex];
recoveredMedians[itemToExchangeIndex] = unrecoveredMedians[itemToExchangeWithIndex];
unrecoveredMedians[itemToExchangeWithIndex] = swap;
}
}
}
return(new GreedyAlgSolution <CoeffType>(settedSolutions)
{
Cost = currentCost
});
}
}
else
{
throw new OdmpProblemException("The sum of medians can't be converted to an integer.");
}
}
}
public EngineLoop(int loopType)
{
_comparer = new InnerComparer(loopType);
_loopType = loopType;
}
/// <summary>
/// Sort array using the specified comparer function
/// </summary>
/// <param name="comparer">Function for comparing array rows</param>
/// <param name="jaggedArray">Jagged array to sort</param>
public static void Sort(Func <int[], int[], int> comparer, int[][] jaggedArray)
{
InnerComparer innerComparer = new InnerComparer(comparer);
Sort(innerComparer, jaggedArray);
}
