Golang 红包算法入门版

import (
    "fmt"
    "math/rand"
    "sync"
    "time"
)

type RedPack struct {
    Id              string
    Num             int // 红包个数
    NumDelivered    int // 已拆包数量
    Amount          int // 红包金额
    AmountDelivered int // 已发放金额
}

func NewRedPack(num int, amount int) *RedPack {
     
    return &RedPack{Num: num, Amount: amount, NumDelivered: 0, AmountDelivered: 0}
}

func (pack *RedPack) get() int {
    if pack.NumDelivered == pack.Num {
        return 0
    }
    // 最后一个红包直接返回
    if pack.NumDelivered == pack.Num-1 {
        amount := pack.Amount - pack.AmountDelivered
        pack.NumDelivered += 1
        pack.AmountDelivered = pack.Amount
        return amount
    }
    // 动态计算红包平均值
    avg := (pack.Amount - pack.AmountDelivered) / (pack.Num - pack.NumDelivered)
    // 随机计算红包金额(1到2倍均值)
    rand.Seed(time.Now().UnixNano())
    calAmount := rand.Intn(2 * avg)
    // 红包金额最少1分
    if calAmount == 0 {
        calAmount = 1
    }
    // 保证后续每个人至少有1分
    if (pack.Amount - pack.AmountDelivered - calAmount) < (pack.Num - pack.NumDelivered - 1) {
        calAmount = pack.Amount - pack.AmountDelivered - (pack.Num - pack.NumDelivered - 1)
    }

    pack.NumDelivered += 1
    pack.AmountDelivered += calAmount
    return calAmount
}

func main() {
    start:=time.Now().UnixNano()/1e6
    wg := &sync.WaitGroup{}
    for i := 0; i < 100000; i++ {
        wg.Add(1)
        go func(wg *sync.WaitGroup) {
            redPack := NewRedPack(10, 10000)
            total := 0
            for i := 0; i < 10; i++ {
                amount := redPack.get()

                total += amount
            }
            wg.Done()
        }(wg)
    }
    wg.Wait(
    // 6核，耗时约9秒
    fmt.Printf("100000个红发发放完毕,耗时：%d ms",(time.Now().UnixNano()/1e6-start))
}

---

思路

1. 必须保证每个红包至少1分钱