waysun一路陽(yáng)光

import java.io.File;
import static java.lang.Math.pow;
import static java.lang.Math.sqrt;
import static java.lang.Math.random;
import java.util.HashMap;
import java.io.FileReader;
import java.io.BufferedReader;
/**
*
* @author dvdface
*/

public class ACOforTSP {


//城市的距離表
private double[][] distance;
//距離的倒數(shù)表
private double[][] heuristic;
//啟發(fā)信息表
private double[][] pheromone;
//權(quán)重
private int alpha, beta;
//迭代的次數(shù)
private int iterationTimes;
//螞蟻的數(shù)量
private int numbersOfAnt;
//蒸發(fā)率
private double rate;

ACOforTSP (String file, int iterationTimes, int numbersOfAnt, int alpha, int beta, double rate) {

//加載文件
this.initializeData(file);
//初始化參數(shù)
this.iterationTimes = iterationTimes;
//設(shè)置螞蟻數(shù)量
this.numbersOfAnt = numbersOfAnt;
//設(shè)置權(quán)重
this.alpha = alpha;
this.beta = beta;
//設(shè)置蒸發(fā)率
this.rate = rate;
}

private void initializeData(String filename) {

//定義內(nèi)部類
class City {

int no;
double x;
double y;

City(int no, double x, double y) {

this.no = no;
this.x = x;
this.y = y;
}

private double getDistance(City city) {

return sqrt(pow((x - city.x), 2) + pow((y - city.y), 2));
}
}

try {
//定義HashMap保存讀取的坐標(biāo)信息
HashMap<Integer, City> map = new HashMap<Integer, City>();
//讀取文件
BufferedReader reader = new BufferedReader(new FileReader(new File(filename)));
for (String str = reader.readLine(); str != null; str = reader.readLine()) {
//將讀到的信息保存入HashMap
if (str.matches("([0-9]+)(\\s*)([0-9]+)(.?)([0-9]*)(\\s*)([0-9]+)(.?)([0-9]*)")) {

String[] data = str.split("(\\s+)");
City city = new City(Integer.parseInt(data[0]),
Double.parseDouble(data[1]),
Double.parseDouble(data[2]));

map.put(city.no, city);
}
}
//分配距離矩陣存儲(chǔ)空間
distance = new double[map.size() + 1][map.size() + 1];
//分配距離倒數(shù)矩陣存儲(chǔ)空間
heuristic = new double[map.size() + 1][map.size() + 1];
//分配信息素矩陣存儲(chǔ)空間
pheromone = new double[map.size() + 1][map.size() + 1];
for (int i = 1; i < map.size() + 1; i++) {
for (int j = 1; j < map.size() + 1; j++) {
//計(jì)算城市間的距離，并存入距離矩陣
distance[j] = map.get(i).getDistance(map.get(j));
//計(jì)算距離倒數(shù)，并存入距離倒數(shù)矩陣
heuristic[j] = 1 / distance[j];
//初始化信息素矩陣
pheromone[j] = 1;
}
}

} catch (Exception exception) {

System.out.println("初始化數(shù)據(jù)失敗！");
}
}

class Ant {

//已訪問(wèn)城市列表
private boolean[] visited;
//訪問(wèn)順序表
private int[] tour;
//已訪問(wèn)城市的個(gè)數(shù)
private int n;
//總的距離
private double total;

Ant() {
//給訪問(wèn)順序表分配空間
tour = new int[distance.length+1];
//已存入城市數(shù)量為n，剛開(kāi)始為0
n = 0;
//將起始城市1,放入訪問(wèn)結(jié)點(diǎn)順序表第一項(xiàng)
tour[++n] = 1;
//給已訪問(wèn)城市結(jié)點(diǎn)分配空間
visited = new boolean[distance.length];
//第一個(gè)城市為出發(fā)城市，設(shè)置為已訪問(wèn)
visited[tour[n]] = true;
}

private int chooseCity() {

//用來(lái)random的隨機(jī)數(shù)
double m = 0;
//獲得當(dāng)前所在的城市號(hào)放入j,如果和j相鄰的城市沒(méi)有被訪問(wèn)，那么加入m
for (int i = 1, j = tour[n]; i < pheromone.length; i++) {

if (!visited) {
m += pow(pheromone[j], alpha) * pow(heuristic[j], beta);
}
}

//保存隨機(jī)到的數(shù)
double p = m * random();
//尋找被隨機(jī)到的城市
double k = 0;
//保存找到的城市
int q = 0;
for (int i = 1, j = tour[n]; k < p; i++) {

if (!visited) {

k += pow(pheromone[j], alpha) * pow(heuristic[j], beta);
q = i;
}
}

return q;
}

private void constructSolution () {

while (n != (distance.length-1) ) {

//選取下一個(gè)城市
int p = chooseCity();
//計(jì)算總的距離
total += distance[tour[n]][p];
//將選取到的城市放入已訪問(wèn)列表
tour[++n] = p;
//將選取到的城市標(biāo)記為已訪問(wèn)
visited[p] = true;
}

//回到起點(diǎn)
total += distance[tour[1]][tour[n]];
//將起點(diǎn)加入訪問(wèn)順序表的最后
tour[++n] = tour[1];
}

private void releasePheromone() {

//釋放信息素的大小
double t = 1/total;
//釋放信息素
for (int i=1;i<tour.length-1;i++) {

pheromone[tour][tour[i+1]] += t;
pheromone[tour[i+1]][tour] += t;
}
}

}

public void go() {

//保存最好的路徑和路徑長(zhǎng)度
double bestTotal = Double.MAX_VALUE;
int[] bestTour = new int[distance.length+1];

//新建螞蟻數(shù)組，用來(lái)引用所創(chuàng)建的螞蟻
Ant[] ant = new Ant[numbersOfAnt];

//進(jìn)行iterationTimes次迭代
while (iterationTimes != 0) {
//初始化新的一批螞蟻（這里用構(gòu)造新的螞蟻代替重置螞蟻狀態(tài)）
for (int i=0; i<numbersOfAnt; i++) {
ant = new Ant();
}

//進(jìn)行一次迭代（即讓所有的螞蟻構(gòu)建一條路徑）
for (int i=0; i<numbersOfAnt; i++) {

ant.constructSolution();
//如果螞蟻構(gòu)建的路徑長(zhǎng)度比上次最好的還好，那么保存這個(gè)長(zhǎng)度和它所走的路徑
if (ant.total<bestTotal) {

bestTotal = ant.total;
System.arraycopy(ant.tour, 1, bestTour, 1, bestTour.length-1);
}
}

//蒸發(fā)信息素
evaporatePheromone();

//釋放信息素
for (int i=0; i<numbersOfAnt; i++) {

ant.releasePheromone();
}

//報(bào)告本次迭代的信息
System.out.format("本次為倒數(shù)第%d次迭代,當(dāng)前最優(yōu)路徑長(zhǎng)度為%10.2f\n",iterationTimes,bestTotal);

//迭代總數(shù)減去1，進(jìn)行下次迭代
iterationTimes--;
}

//輸出最好的路徑長(zhǎng)度
System.out.format("得到的最優(yōu)的路徑長(zhǎng)度為:%10.2f\n",bestTotal);
//輸出最好的路徑
System.out.println("最優(yōu)路徑如下：");
for (int i=1; i<bestTour.length; i++) {

System.out.print("→"+bestTour);
}
}

private void evaporatePheromone() {

for (int i = 1; i < pheromone.length; i++)
for (int j = 1; j < pheromone.length; j++) {

pheromone[j] *= 1-rate;
}

}
}