编辑代码

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

public class BeanKnapsack {

    static class Bean {
        int weight;
        int value;

        public Bean(int weight, int value) {
            this.weight = weight;
            this.value = value;
        }
    }

    public static double maxBeanValue(Bean[] beans, int capacity) {
        // 按单位重量的价值降序排序
        Arrays.sort(beans, Comparator.comparingDouble(bean -> (double) bean.value / bean.weight));

        double maxValue = 0;
        for (int i = beans.length - 1; i >= 0; i--) {
            if (capacity >= beans[i].weight) {
                maxValue += beans[i].value;
                capacity -= beans[i].weight;
            } else {
                // 部分放入
                maxValue += (double) beans[i].value / beans[i].weight * capacity;
                break;
            }
        }

        return maxValue;
    }

    public static void main(String[] args) {
        Bean[] beans = {new Bean(2, 10), new Bean(3, 5), new Bean(5, 15), new Bean(7, 7), new Bean(1, 6)};
        int capacity = 15;
        double result = maxBeanValue(beans, capacity);
        System.out.println("（20052248田雨瑶）背包中豆子的最大值: " + result);
    }
}