遗传算法解决tsp问题java
时间: 2023-07-29 18:10:03 浏览: 55
遗传算法可以用来解决TSP(Traveling Salesman Problem)问题,其中目标是找到最短路径来访问一系列城市。下面是一个简单的用Java实现遗传算法解决TSP问题的示例代码:
```java
import java.util.*;
public class TSPGeneticAlgorithm {
private int populationSize;
private double mutationRate;
private int tournamentSize;
private boolean elitism;
public TSPGeneticAlgorithm(int populationSize, double mutationRate, int tournamentSize, boolean elitism) {
this.populationSize = populationSize;
this.mutationRate = mutationRate;
this.tournamentSize = tournamentSize;
this.elitism = elitism;
}
public Route evolvePopulation(Route initialPopulation) {
Population population = new Population(populationSize, initialPopulation);
Random random = new Random();
if (elitism) {
population.saveBestRoute();
}
while (!population.isConverged()) {
Population newPopulation = new Population(populationSize);
if (elitism) {
newPopulation.saveBestRoute();
}
for (int i = elitism ? 1 : 0; i < populationSize; i++) {
Route parent1 = tournamentSelection(population, random);
Route parent2 = tournamentSelection(population, random);
Route child = crossover(parent1, parent2, random);
mutate(child, random);
newPopulation.setRoute(i, child);
}
population = newPopulation;
}
return population.getBestRoute();
}
private Route tournamentSelection(Population population, Random random) {
Population tournament = new Population(tournamentSize);
for (int i = 0; i < tournamentSize; i++) {
int randomIndex = random.nextInt(populationSize);
tournament.setRoute(i, population.getRoute(randomIndex));
}
return tournament.getBestRoute();
}
private Route crossover(Route parent1, Route parent2, Random random) {
Route child = new Route(parent1.getSize());
int startPos = random.nextInt(parent1.getSize());
int endPos = random.nextInt(parent1.getSize());
for (int i = 0; i < child.getSize(); i++) {
if (startPos < endPos && i > startPos && i < endPos) {
child.setCity(i, parent1.getCity(i));
} else if (startPos > endPos) {
if (!(i < startPos && i > endPos)) {
child.setCity(i, parent1.getCity(i));
}
}
}
for (int i = 0; i < parent2.getSize(); i++) {
if (!child.containsCity(parent2.getCity(i))) {
for (int j = 0; j < child.getSize(); j++) {
if (child.getCity(j) == null) {
child.setCity(j, parent2.getCity(i));
break;
}
}
}
}
return child;
}
private void mutate(Route route, Random random) {
for (int i = 0; i < route.getSize(); i++) {
if (random.nextDouble() < mutationRate) {
int swapIndex = random.nextInt(route.getSize());
route.swapCities(i, swapIndex);
}
}
}
}
```
这只是一个简单的示例,你可以根据需要进行进一步的改进和优化。希望对你有所帮助!
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