public IEnumerable <Money> Decompose(IEnumerable <Money> myInputCoinEffectiveValues, IEnumerable <Money> othersInputCoinEffectiveValues)
{
var histogram = GetDenominationFrequencies(othersInputCoinEffectiveValues.Concat(myInputCoinEffectiveValues));
// Filter out and order denominations those have occurred in the frequency table at least twice.
var preFilteredDenoms = histogram
.Where(x => x.Value > 1)
.OrderByDescending(x => x.Key)
.Select(x => x.Key)
.ToArray();
// Filter out denominations very close to each other.
// Heavy filtering on the top, little to no filtering on the bottom,
// because in smaller denom levels larger users are expected to participate,
// but on larger denom levels there's little chance of finding each other.
var increment = 0.5 / preFilteredDenoms.Length;
List <ulong> denoms = new();
var currentLength = preFilteredDenoms.Length;
foreach (var denom in preFilteredDenoms)
{
var filterSeverity = 1 + currentLength * increment;
if (!denoms.Any() || denom <= (denoms.Last() / filterSeverity))
{
denoms.Add(denom);
}
currentLength--;
}
var myInputs = myInputCoinEffectiveValues.ToArray();
var myInputSum = myInputs.Sum();
var remaining = myInputSum;
var remainingVsize = AvailableVsize;
var setCandidates = new Dictionary <int, (IEnumerable <Money> Decomp, Money Cost)>();
var random = new Random();
// How many times can we participate with the same denomination.
var maxDenomUsage = random.Next(2, 8);
// Create the most naive decomposition for starter.
List <Money> naiveSet = new();
bool end = false;
foreach (var denomPlusFee in preFilteredDenoms.Where(x => x <= remaining))
{
var denomUsage = 0;
while (denomPlusFee <= remaining)
{
// We can only let this go forward if at least 2 output can be added (denom + potential change)
if (remaining < MinAllowedOutputAmountPlusFee || remainingVsize < 2 * OutputSize)
{
end = true;
break;
}
naiveSet.Add(denomPlusFee);
remaining -= denomPlusFee;
remainingVsize -= OutputSize;
denomUsage++;
// If we reached the limit, the rest will be change.
if (denomUsage >= maxDenomUsage)
{
end = true;
break;
}
}
if (end)
{
break;
}
}
var loss = 0UL;
if (remaining >= MinAllowedOutputAmountPlusFee)
{
naiveSet.Add(remaining);
}
else
{
// This goes to miners.
loss = remaining;
}
// This can happen when smallest denom is larger than the input sum.
if (naiveSet.Count == 0)
{
naiveSet.Add(remaining);
}
HashCode hash = new();
foreach (var item in naiveSet.OrderBy(x => x))
{
hash.Add(item);
}
setCandidates.Add(
hash.ToHashCode(), // Create hash to ensure uniqueness.
(naiveSet, loss + (ulong)naiveSet.Count * OutputFee)); // The cost is the remaining + output cost.
// Create many decompositions for optimization.
Decomposer.StdDenoms = denoms.Where(x => x <= myInputSum).Select(x => (long)x).ToArray();
foreach (var(sum, count, decomp) in Decomposer.Decompose((long)myInputSum, (long)Math.Max(loss, 0.5 * (ulong)MinAllowedOutputAmountPlusFee), Math.Min(8, Math.Max(5, naiveSet.Count))))
{
var currentSet = Decomposer.ToRealValuesArray(
decomp,
count,
Decomposer.StdDenoms).Select(Money.Satoshis).ToList();
hash = new();
foreach (var item in currentSet.OrderBy(x => x))
{
hash.Add(item);
}
setCandidates.TryAdd(hash.ToHashCode(), (currentSet, myInputSum - (ulong)currentSet.Sum() + (ulong)count * OutputFee)); // The cost is the remaining + output cost.
}
var denomHashSet = preFilteredDenoms.ToHashSet();
var finalCandidates = setCandidates.Select(x => x.Value).ToList();
finalCandidates.Shuffle();
var orderedCandidates = finalCandidates
.OrderBy(x => x.Cost) // Less cost is better.
.ThenBy(x => x.Decomp.All(x => denomHashSet.Contains(x)) ? 0 : 1) // Prefer no change.
.Select(x => x).ToList();
var finalCandidate = orderedCandidates.First().Decomp;
foreach (var candidate in orderedCandidates)
{
if (random.NextDouble() < 0.5)
{
finalCandidate = candidate.Decomp;
break;
}
}
finalCandidate = finalCandidate.Select(x => x - OutputFee);
var totalOutputAmount = finalCandidate.Sum(x => x + OutputFee);
if (totalOutputAmount > myInputSum)
{
throw new InvalidOperationException("The decomposer is creating money. Aborting.");
}
if (totalOutputAmount + MinAllowedOutputAmountPlusFee < myInputSum)
{
throw new InvalidOperationException("The decomposer is losing money. Aborting.");
}
var totalOutputVsize = finalCandidate.Count() * OutputSize;
if (totalOutputVsize > AvailableVsize)
{
throw new InvalidOperationException("The decomposer created more outputs than it can. Aborting.");
}
return(finalCandidate);
}
