编辑代码

package greedy;

import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;

class Item {
    public String name;
    public double totalWeight;
    public double totalValue;

    Item(String itemName, double weight, double value) {
        this.name = itemName;
        this.totalWeight = weight;
        this.totalValue = value;
    }

     Item(Item item) {
        this.name = item.name;
        this.totalWeight = item.totalWeight;
        this.totalValue = item.totalValue;
    }
}

public class Backpack {
    public static LinkedList<Item> packBean(int packCapacity, Item[] items){
         LinkedList<Item> beans = new LinkedList<Item>(); // 记录需要装包的豆子

         //按照单价从高到低进行排序
         Arrays.sort(items, new Comparator<Item>() {
             public int compare(Item left, Item right) {
                 double leftUnitPrice = left.totalValue/left.totalWeight;
                 double rightUnitPrice = right.totalValue/right.totalWeight;
                 if (leftUnitPrice > rightUnitPrice){
                     return -1;
                 }
                 else if (leftUnitPrice == rightUnitPrice) {
                     return 0;
                 }
                 else {
                     return 1;
                 }
             }
         }); 

         //从高到低依次取出豆子
         int leftPackCapacity = packCapacity;
         for (int i = 0; i < items.length; ++i) {
             if (leftPackCapacity > items[i].totalWeight) {
                 leftPackCapacity -= items[i].totalWeight;
                 beans.add(new Item(items[i]));
             }
             else {
                 double unitPrice = items[i].totalValue/items[i].totalWeight;
                 double packWeight = leftPackCapacity;
                 double packValue = packWeight * unitPrice;
                 beans.add(new Item(items[i].name, packWeight, packValue));
                 leftPackCapacity = 0;
                 break;
             }
         }

         return beans;
    }
    public static void test() {
        Item[] items = {
            new Item("黄豆", 100, 100),
            new Item("绿豆", 30, 90),
            new Item("红豆", 60, 120),
            new Item("黑豆", 20, 80),
            new Item("青豆", 50, 75)
        };

        LinkedList<Item> beans = packBean(100, items);

        double maxValue = 0;

        System.out.println("装了如下物品：");
        for (int i = 0; i < beans.size(); ++i) {
            maxValue += beans.get(i).totalValue;
            System.out.println(beans.get(i).name + " " + beans.get(i).totalWeight);
        }

        System.out.println("总价值：" + maxValue);

	}

}