用java实现退火算法

以下是Java实现退火算法的示例代码：

import java.util.Random;

public class SimulatedAnnealing {
    private double currentEnergy; // 当前能量
    private double temperature; // 温度
    private double coolingRate; // 降温率
    private int[] currentState; // 当前状态
    private int[] bestState; // 最优状态
    private double bestEnergy; // 最优能量
    private int[] lowerBound; // 下界
    private int[] upperBound; // 上界

    public SimulatedAnnealing(double temperature, double coolingRate, int[] lowerBound, int[] upperBound) {
        this.temperature = temperature;
        this.coolingRate = coolingRate;
        this.lowerBound = lowerBound;
        this.upperBound = upperBound;
        currentState = new int[lowerBound.length];
        bestState = new int[lowerBound.length];
        for (int i = 0; i < lowerBound.length; i++) {
            currentState[i] = lowerBound[i] + new Random().nextInt(upperBound[i] - lowerBound[i] + 1);
            bestState[i] = currentState[i];
        }
        currentEnergy = calculateEnergy(currentState);
        bestEnergy = currentEnergy;
    }

    // 计算能量
    private double calculateEnergy(int[] state) {
        // 这里以求函数最小值为例
        double energy = 0;
        for (int i = 0; i < state.length; i++) {
            energy += Math.pow(state[i], 2); // 求平方和
        }
        return energy;
    }

    // 退火过程
    public void anneal() {
        while (temperature > 1) {
            int[] nextState = new int[currentState.length];
            for (int i = 0; i < currentState.length; i++) {
                // 生成下一个状态
                nextState[i] = currentState[i] + new Random().nextInt(3) - 1;
                // 如果越界了则重新生成
                if (nextState[i] < lowerBound[i] || nextState[i] > upperBound[i]) {
                    nextState[i] = currentState[i];
                }
            }
            double nextEnergy = calculateEnergy(nextState);
            double deltaEnergy = nextEnergy - currentEnergy;
            // 如果新状态更优，则接受
            if (deltaEnergy < 0 || Math.exp(-deltaEnergy / temperature) > new Random().nextDouble()) {
                currentState = nextState;
                currentEnergy = nextEnergy;
                // 更新最优状态
                if (currentEnergy < bestEnergy) {
                    bestState = currentState.clone();
                    bestEnergy = currentEnergy;
                }
            }
            // 降温
            temperature *= coolingRate;
        }
    }

    // 获取最优状态
    public int[] getBestState() {
        return bestState;
    }

    // 获取最优能量
    public double getBestEnergy() {
        return bestEnergy;
    }
}

示例用法：

public class Main {
    public static void main(String[] args) {
        int[] lowerBound = {-10, -10, -10};
        int[] upperBound = {10, 10, 10};
        SimulatedAnnealing sa = new SimulatedAnnealing(100, 0.95, lowerBound, upperBound);
        sa.anneal();
        int[] bestState = sa.getBestState();
        double bestEnergy = sa.getBestEnergy();
        System.out.println("最优状态：" + Arrays.toString(bestState));
        System.out.println("最优能量：" + bestEnergy);
    }
}