字节跳动笔试题2020 （抖音电商）

题目: 写一个以权重来进行随机分配的程序。

拿到这个题的时候我思考了一下，幸好我之前看了Ribbon 的权重算法。核心的思想就是把所有的权重值加起来，做随机值计算最终确定随机值在权重总值中的位置，从而确定是那个数据。

import java.util.ArrayList;
import java.util.List;

public class Test12 {

    //权重算法
    public Weight getWeight(List<Weight> list){
        int totalWeight = 0;
        for(Weight weight:list){
            totalWeight += weight.getValue();
        }

        double random = Math.random();
        Integer weightValue = new Double(Math.ceil(random*totalWeight)).intValue();
        totalWeight = 0;
        for(Weight weight:list){
            totalWeight += weight.getValue();
            if(weightValue - totalWeight<=0){
                return weight;
            }
        }
        return null;
    }

    public static void main(String[] args) {
        Weight weight = new Weight(1,"A");
        Weight weight2 = new Weight(2,"B");
        Weight weight3 = new Weight(3,"C");

        List<Weight> list = new ArrayList<>();
        list.add(weight);
        list.add(weight2);
        list.add(weight3);
        Test12 test12 = new Test12();
        Weight returnWeight = test12.getWeight(list);

        System.out.println(returnWeight);

    }
}

class Weight{
    private Integer value;
    private String name;

    public Weight(Integer value,String name){
        this.value = value;
        this.name = name;
    }

    public Integer getValue() {
        return value;
    }
}

输出结果：