golang 随机概率的权重抽奖实现

package main

import (
    "encoding/json"
    "fmt"
    "math"
    "math/rand"
    "sort"
    "time"
)

type Prize struct {
    PlayerId int64
    Weight   int
}

func main() {
    //设置奖项名称、权重等数组
    var prizes = make([]*Prize, 0)
    for i := 0; i < 4; i++ {
        prize := &Prize{
            PlayerId: int64(i) + 10000,
            Weight:   (5 - i) * 10,
        }
        prizes = append(prizes, prize)
    }
    for _, v := range prizes {
        fmt.Println(v.PlayerId, v.Weight)
    }

    RandomDraw(prizes)
}

// 权重随机抽奖
func RandomDraw(prizes []*Prize) int64 {
    //权重累加求和
    var weightSum int
    for _, v := range prizes {
        weightSum += v.Weight
    }

    //生成一个权重随机数，介于0-weightSum之间
    rand.Seed(time.Now().UnixNano())
    randomNum := rand.Intn(weightSum)

    //权重数组重组并排序
    randomNumTmp := &Prize{PlayerId: -1, Weight: randomNum}
    concatWeightArr := make([]*Prize, 0)
    aa, _ := json.Marshal(prizes)
    _ = json.Unmarshal(aa, &concatWeightArr)
    fmt.Println("concatWeightArr：", concatWeightArr)
    concatWeightArr = append(concatWeightArr, randomNumTmp) //将随机数加入权重数组

    //将包含随机数的新权重数组按从小到大（升序）排序
    sort.Slice(concatWeightArr, func(i, j int) bool {
        return concatWeightArr[i].Weight < concatWeightArr[j].Weight
    })
    sort.Slice(prizes, func(i, j int) bool {
        return prizes[i].Weight < prizes[j].Weight
    })

    for _, v := range prizes {
        fmt.Println(*v)
    }

    //索引权重随机数的数组下标
    var randomNumIndex = -1 //索引随机数在新权重数组中的位置
    for p, v := range concatWeightArr {
        if v.Weight == randomNum {
            randomNumIndex = p
        }
    }
    randomNumIndexTmp := math.Min(float64(randomNumIndex), float64(len(prizes)-1)) //权重随机数的下标不得超过奖项数组的长度-1，重新计算随机数在奖项数组中的索引位置
    randomNumIndex = int(randomNumIndexTmp)

    //取出对应奖项
    res := prizes[randomNumIndex] //从奖项数组中取出本次抽奖结果
    fmt.Println("本次抽奖结果：", res.PlayerId)
    return res.PlayerId
}