Java貪心算法求解多機調度問題

問題描述:

貪心算法

package 貪心;

import java.util.*;

public class Greedy2 {
    public static void main (String[] args) {
        int[] a = {5, 6, 3, 2, 8, 8 ,9};
        System.out.println("最優解"+greedy(a,3));
        //運行結果
        //將機器1從0到9分配給作業7
        //將機器2從0到8分配給作業5
        //將機器3從0到8分配給作業6
        //將機器3從8到14分配給作業2
        //將機器2從8到13分配給作業1
        //將機器1從9到12分配給作業3
        //將機器1從12到14分配給作業4
        //最優解14
    }

    private static int greedy (int[] arr, int m) {
        int n = arr.length;
        int sum = 0;
        if (n <= m) {
            for (int i = 0; i < n; i++) {
                if (sum < arr[i]) {
                    sum = arr[i];
                }
            }
            System.out.println("爲每一臺機器分工一個作業");
            return sum;
        }
        List<Job> jobs = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            Job job = new Job(i + 1, arr[i]);
            jobs.add(job);
        }
        Collections.sort(jobs);
        LinkedList<Machine> machines = new LinkedList<>();
        for (int i = 1; i <= m; i++) {
            Machine machine = new Machine(i, 0);
            machines.add(machine);
        }
        for (int i = 0; i < n; i++) {
            Collections.sort(machines);
            Machine mac =machines.peek();
            System.out.println("將機器" + mac.getId() + "從" + mac.getAvaile() + "到" + (mac.getAvaile() + jobs.get(i).getTime()) + "分配給作業" + jobs.get(i).getId());
            int a = mac.getAvaile() + jobs.get(i).getTime();
            mac.setAvaile(a);

            sum = a;

        }

        return sum;
    }
}

class Job implements Comparable {
    private int id;
    private int time;

    public Job (int id, int time) {
        this.id = id;
        this.time = time;
    }

    public int getId () {
        return id;
    }

    public void setId (int id) {
        this.id = id;
    }

    public int getTime () {
        return time;
    }

    public void setTime (int time) {
        this.time = time;
    }

    @Override
    public int compareTo (Object o) {
        int otherTime = ((Job) o).getTime();
        if (this.time < otherTime) return 1;
        if (this.time == otherTime) return 0;
        return -1;
    }
}

class Machine implements Comparable {
    private int id;
    private int availe;


    public Machine (int id, int availe) {
        this.id = id;
        this.availe = availe;
    }

    public int getId () {
        return id;
    }

    public void setId (int id) {
        this.id = id;
    }

    public int getAvaile () {
        return availe;
    }

    public void setAvaile (int availe) {
        this.availe = availe;
    }

    @Override
    public int compareTo (Object o) {
        int otherTime = ((Machine) o).getAvaile();
        if (this.availe < otherTime) return -1;
        if (this.availe == otherTime) return 0;
        return 1;
    }
}