/// <summary>
/// Gets variable, which indicates creative row
/// </summary>
public string GetCreativeVariable(SimplexTable table, ProblemForGomory problem)
{
var maxVariables = new List<string>();
var maxFractionalPart = new Fraction();
foreach (var basisVariable in table.GetBasis())
{
if (!problem.WholeConstraints.Contains(basisVariable.Key))
continue;
var fractionalPart = GetFractionalPart(basisVariable.Value);
if (fractionalPart > maxFractionalPart)
{
maxVariables.Clear();
maxFractionalPart = fractionalPart;
}
if (fractionalPart == maxFractionalPart)
maxVariables.Add(basisVariable.Key);
}
if (maxVariables.Count == 1) return maxVariables[0];
maxFractionalPart = new Fraction();
var maxVariable = string.Empty;
foreach (var variable in maxVariables)
{
var sumOfFractionalParts = new Fraction();
foreach (var rowVariable in table.GetRow(variable).Key)
sumOfFractionalParts += GetFractionalPart(rowVariable);
var ratio = sumOfFractionalParts != 0
? GetFractionalPart(table.GetRow(variable).Value) / sumOfFractionalParts
: new Fraction();
if (ratio <= maxFractionalPart) continue;
maxFractionalPart = ratio;
maxVariable = variable;
}
return maxVariable;
}
private bool HaveNegativeFreeCoefficients(SimplexTable table)
{
foreach (var coefficient in table.GetBasis().Values)
if (coefficient < 0)
return true;
return false;
}
private bool HaveNegativeRowsWithoutNegativeElements(SimplexTable table)
{
foreach (var basisVar in table.GetBasis())
{
if (basisVar.Value >= 0) continue;
var haveNegative = false;
foreach (var tableElement in table.GetRow(basisVar.Key).Key)
{
if (tableElement >= 0) continue;
haveNegative = true;
break;
}
if (!haveNegative) return true;
}
return false;
}
private static LppResult GetResult(SimplexTable table, ICollection<string> varsWithMaxCoefficient)
{
var point = new Dictionary<string, Fraction>();
var basis = table.GetBasis();
var isCorrect = true;
foreach (var variable in table.Variables)
{
if (varsWithMaxCoefficient.Contains(variable) && basis.ContainsKey(variable)
&& basis[variable] != 0)
isCorrect = false;
point.Add(variable, (basis.ContainsKey(variable) ? basis[variable] : new Fraction()));
}
return new LppResult(point, isCorrect ? table.CalculateFunctionValue().FreeCoefficient : null);
}
