public SolutionCandidate Clone()
{
SolutionCandidate Clone = new SolutionCandidate()
{
LowerBound = this.LowerBound,
Assignments = this.Assignments
};
return(Clone);
}
public void EvaluateCost()
{
BuildMinimumCostTable(NumberOfAgents, NumberOFTasks);
SolutionCandidate currentSolution = new SolutionCandidate();
currentSolution.Assignments = new System.Collections.Generic.List <int>();
for (int i = 0; i < NumberOfAgents; i++)
{
currentSolution.Assignments.Add(i);
currentSolution.LowerBound += this.CostMatrix[NumberOfAgents, NumberOfAgents];
}
SolutionCandidatePriorityQueue.Add(new SolutionCandidate()
{
Assignments = new System.Collections.Generic.List <int>()
});
while (!SolutionCandidatePriorityQueue.IsEmpty)
{
// Get next candidate. If a priority queue is used, the "next" candidate is the
// most promising (with lowest lower bound):
var candidate = SolutionCandidatePriorityQueue.DeleteMin();
// Branch out:
for (int i = 0; i < NumberOFTasks; i++)
{
// Only create the branch if the current task is not already taken by an agent:
if (!candidate.Assignments.Contains(i))
{
var branch = (SolutionCandidate)candidate.Clone();
branch.Assignments.Add(i);
branch.LowerBound = CalculateLowerBound(branch);
// Only use the generated branch if its lower bound is strictly better than
// the currently found solution cost.
// This is the "bound" part in "Branch and Bound":
if (currentSolution.LowerBound < branch.LowerBound)
{
continue;
}
if (branch.Assignments.Count == NumberOfAgents)
{
currentSolution = branch;
}
else
{
this.SolutionCandidatePriorityQueue.Add(branch);
}
}
}
}
}
private int CalculateLowerBound(SolutionCandidate candidate)
{
int lowerBound = 0;
int Agent = 0;
// Add the costs for the already fixed agents:
for (; Agent < candidate.Assignments.Count; Agent++)
{
var task = candidate.Assignments[Agent];
lowerBound += this.CostMatrix[Agent, task];
}
for (int j = Agent; j < MinimumCosts.Length; j++)
{
lowerBound += MinimumCosts[j];
}
return(lowerBound);
}