public void MergeWithBest(Solution best,Random random)
{
Difference diff = new Difference(this, best);
if (diff.Distance != 0)
{
int position = random.Next(diff.Distance);
position = diff.Positions[position];
City newBest = best.Cities[position];
//we do have new city, so there's need for correction
//find current instance
City curSelected = Cities[position];
Cities[Cities.IndexOf(newBest)] = curSelected;
Cities[position] = newBest;
}
}
public Difference(Solution from, Solution to)
{
var i1 = from.Cities.GetEnumerator();
var i2 = to.Cities.GetEnumerator();
Positions = new List<int>();
for(int i = 0; i < from.Cities.Count; ++i)
{
i1.MoveNext();
i2.MoveNext();
if (i1.Current != i2.Current)
{
Positions.Add(i);
}
}
}
private void Shuffle(Solution s)
{
int n = s.Cities.Count;
while (n > 1)
{
--n;
int k = randomizer.Next(n + 1);
s.SwapCities(k, n);
}
}
private void LocalSearch(Solution s, State state)
{
int m, n;
double baseEvaluation = s.Evaluate(state.Warehouse, state.K);
for (int i = 0; i < LSTrials; ++i)
{
m = randomizer.Next(s.Cities.Count);
do{
n = randomizer.Next(s.Cities.Count);
}while(m == n);
s.SwapCities(m, n);
if (s.Evaluate(state.Warehouse, state.K) < baseEvaluation)
{
//better permutation
baseEvaluation = s.Evaluation;
}
else
{
//worse permutation, we go back to previous one
s.SwapCities(m, n);
s.Evaluate(state.Warehouse, state.K);
}
}
}
private IList<Solution> Initialize(State s)
{
IList<Solution> solutions = new List<Solution>();
Solution solution;
solutions.Add(GenerateGreedySolution(s));
Console.WriteLine(solutions[0].Evaluate(s.Warehouse, s.K));
for (int i = 1; i < s.PopulationSize; ++i)
{
solution = new Solution(new List<City>(s.Cities));
Shuffle(solution);
solutions.Add(solution);
}
return solutions;
}