// 对parent1和parent2进行交叉操作，生成新的 tour 路径
public static Tour crossover(Tour parent1, Tour parent2)
{
// Create new child tour
Tour child = new Tour(parent1.tourSize());
// startPos endPos之间的序列，会被遗传到下一代。 (如果startPos<endPos,就是取反)
int startPos = (int)(new Random().NextDouble() * parent1.tourSize());
int endPos = (int)(new Random().NextDouble() * parent1.tourSize());
// Loop and add the sub tour from parent1 to our child
for (int i = 0; i < child.tourSize(); i++)
{
// If our start position is less than the end position
if (startPos < endPos && i > startPos && i < endPos)
{
child.setCity(i, parent1.getCity(i));
} // If our start position is larger
else if (startPos > endPos)
{
if (!(i < startPos && i > endPos))
{
child.setCity(i, parent1.getCity(i));
}
}
}
// 由于child已经继承了parent1的部分city. 下面就是找 parent2中还被child继承的那些city
// 要保证city的唯一性
for (int i = 0; i < parent2.tourSize(); i++)
{
// If child doesn't have the city add it
if (!child.containsCity(parent2.getCity(i)))
{
// Loop to find a spare position in the child's tour
for (int ii = 0; ii < child.tourSize(); ii++)
{
// Spare position found, add city
if (child.getCity(ii) == null)
{
child.setCity(ii, parent2.getCity(i));
break;
}
}
}
}
return(child);
}
// 突变操作。随机交换
private static void mutate(Tour tour)
{
// Loop through tour cities
for (int tourPos1 = 0; tourPos1 < tour.tourSize(); tourPos1++)
{
// Apply mutation rate
if (new Random().NextDouble() < mutationRate)
{
// Get a second random position in the tour
int tourPos2 = (int)(tour.tourSize() * new Random().NextDouble());
// Get the cities at target position in tour
City city1 = tour.getCity(tourPos1);
City city2 = tour.getCity(tourPos2);
// Swap them around
tour.setCity(tourPos2, city1);
tour.setCity(tourPos1, city2);
}
}
}