private void CurrencyBtn_Click(object sender, EventArgs e)
{
OutputTxt.Text = "";
Digraph graph = new Digraph();
Parser p = new Parser();
graph = p.Parse(FilePathTxt.Text, ref OutputTxt);
CurrencyVertex from = graph.nodes.Find(x => x.Symbol == FromTxt.Text);
CurrencyVertex to = graph.nodes.Find(x => x.Symbol == ToTxt.Text);
if (from == null)
{
OutputTxt.Text = "There is no such currency in the input file: " + FromTxt.Text;
}
else if (to == null)
{
OutputTxt.Text = "There is no such currency in the input file: " + ToTxt.Text;
}
else if (!double.TryParse(ExchangeAmountTxt.Text, out double moneyAtSource))
{
OutputTxt.Text = "Initial amount of money has to be a number";
}
else if (from.Equals(to))
{
OutputTxt.Text = "There is no need to convert " + from.Symbol + " to " + to.Symbol + ":)";
}
else
{
var exchange = new BestExchange(graph);
try
{
List <CurrencyVertex> path = exchange.Find(from, to, moneyAtSource, out double moneyAtFinish);
if (path == null)
{
OutputTxt.Text = "There is no exchange possible between given currencies";
}
else
{
var outputText = exchange.GenerateOutput(path);
OutputTxt.Text = outputText;
}
}
catch (OutOfMemoryException)
{
OutputTxt.Text = "There is an infinite arbitrage on the way!";
}
}
GraphImg.Focus();
}
public List <CurrencyVertex> Find(CurrencyVertex src, CurrencyVertex to, double moneyAtStart, out double moneyAtFinish)
{
src.MoneyAt = moneyAtStart;
src.MinDistance = 0;
moneyAtFinish = 0;
foreach (var edge in edges)
{
edge.FinishVertex.Prev = edge.StartVertex;
}
for (int i = 0; i < vertices.Count - 1; ++i)
{
foreach (var edge in edges)
{
if (edge.StartVertex.MinDistance == int.MaxValue)
{
continue;
}
double newMoneyAtDest;
double newDistance;
if (edge.FeeType == (int)ExchangeEdge.ChargeType.Percent)
{
newMoneyAtDest = edge.StartVertex.MoneyAt * edge.Weight * (1 - edge.Charge);
newDistance = Inverse(newMoneyAtDest);
if (newDistance < edge.FinishVertex.MinDistance)
{
edge.FinishVertex.MinDistance = newDistance;
edge.FinishVertex.Prev = edge.StartVertex;
edge.FinishVertex.MoneyAt = newMoneyAtDest;
}
}
else if (edge.FeeType == (int)ExchangeEdge.ChargeType.Standing)
{
newMoneyAtDest = edge.StartVertex.MoneyAt * edge.Weight - edge.Charge;
newDistance = Inverse(newMoneyAtDest);
if (newDistance < edge.FinishVertex.MinDistance)
{
edge.FinishVertex.MinDistance = newDistance;
edge.FinishVertex.Prev = edge.StartVertex;
edge.FinishVertex.MoneyAt = newMoneyAtDest;
}
}
}
}
path.Add(to);
CurrencyVertex last = vertices.Find(x => x.Equals(to));
CurrencyVertex first = vertices.Find(x => x.Equals(src));
while (last.Prev != first)
{
last = last.Prev;
if (last == null)
{
return(null);
}
path.Add(last);
}
path.Add(src);
path.Reverse();
moneyAtFinish = vertices.Find(x => x.Equals(to)).MoneyAt;
return(path);
}
public List <CurrencyVertex> Find(double moneyAtStart)
{
for (int i = 0; i < vertices.Count; i++)
{
vertices[i].MinDistance = 0;
vertices[i].MoneyAt = moneyAtStart;
for (int j = 0; j < vertices.Count - 1; ++j)
{
foreach (var edge in edges)
{
if (edge.StartVertex.MinDistance == int.MaxValue)
{
continue;
}
double newMoneyAtDest;
double newDistance;
if (edge.FeeType == (int)ExchangeEdge.ChargeType.Percent)
{
newMoneyAtDest = edge.StartVertex.MoneyAt * edge.Weight * (1 - edge.Charge);
newDistance = Inverse(newMoneyAtDest);
if (newDistance < edge.FinishVertex.MinDistance)
{
edge.FinishVertex.MinDistance = newDistance;
edge.FinishVertex.Prev = edge.StartVertex;
edge.FinishVertex.MoneyAt = newMoneyAtDest;
}
}
else if (edge.FeeType == (int)ExchangeEdge.ChargeType.Standing)
{
newMoneyAtDest = edge.StartVertex.MoneyAt * edge.Weight - edge.Charge;
newDistance = Inverse(newMoneyAtDest);
if (newDistance < edge.FinishVertex.MinDistance)
{
edge.FinishVertex.MinDistance = newDistance;
edge.FinishVertex.Prev = edge.StartVertex;
edge.FinishVertex.MoneyAt = newMoneyAtDest;
}
}
}
}
foreach (var edge in edges)
{
if (edge.FeeType == (int)ExchangeEdge.ChargeType.Percent)
{
double moneyAtFinish = 0;
moneyAtFinish = edge.StartVertex.MoneyAt * edge.Weight * (1 - edge.Charge);
edge.ArbWeight = -Math.Log(moneyAtFinish / edge.StartVertex.MoneyAt);
edge.Weight = edge.ArbWeight;
}
else if (edge.FeeType == (int)ExchangeEdge.ChargeType.Standing)
{
double moneyAtFinish = 0;
moneyAtFinish = edge.StartVertex.MoneyAt * edge.Weight - edge.Charge;
edge.ArbWeight = -Math.Log(moneyAtFinish / edge.StartVertex.MoneyAt);
edge.Weight = edge.ArbWeight;
}
}
vertices[i].ArbMinDistance = 0;
for (int k = 0; k < vertices.Count - 1; ++k)
{
foreach (var edge in edges)
{
if (edge.StartVertex.ArbMinDistance == int.MaxValue)
{
continue;
}
double newArbDistance = edge.StartVertex.ArbMinDistance + edge.Weight;
if (newArbDistance < edge.FinishVertex.ArbMinDistance)
{
edge.FinishVertex.ArbMinDistance = newArbDistance;
edge.FinishVertex.ArbPrev = edge.StartVertex;
}
}
}
List <CurrencyVertex> cycle = new List <CurrencyVertex>();
foreach (var edge in edges)
{
if (HasCycle(edge) && edge.StartVertex.ArbMinDistance != int.MaxValue)
{
CurrencyVertex vertex = edge.StartVertex;
while (!vertex.Equals(edge.FinishVertex) && !vertex.Visited)
{
cycle.Add(vertex);
vertex.Visited = true;
vertex = vertex.ArbPrev;
}
cycle.Add(edge.FinishVertex);
cycle.Reverse();
return(cycle);
}
}
}
return(null);
}