package main

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

var wg sync.WaitGroup
var mutex sync.Mutex
var tickets = 100

func main() {
    rand.Seed(time.Now().UnixNano())
    wg.Add(4)
    var chan1 = make(chan int, 1)
    var chan2 = make(chan int, 1)
    var chan3 = make(chan int, 1)
    var chan4 = make(chan int, 1)
    go mai("1号窗口", chan1)
    go mai("2号窗口", chan2)
    go mai("3号窗口", chan3)
    go mai("4号窗口", chan4)
    for i := 0; i <= 103; i++ {
        time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
        switch i % 4 {
        case 0:
            fmt.Println(i+1, "号顾客正在1号窗口买票")
            chan1 <- i
        case 1:
            fmt.Println(i+1, "号顾客正在2号窗口买票")
            chan2 <- i
        case 2:
            fmt.Println(i+1, "号顾客正在3号窗口买票")
            chan3 <- i
        case 3:
            fmt.Println(i+1, "号顾客正在4号窗口买票")
            chan4 <- i

        }

    }
    wg.Wait()
    fmt.Println("结束")
}
func mai(num string, ch chan int) {
    rand.Seed(time.Now().UnixNano())
    defer wg.Done()
    for {
        i := <-ch
        mutex.Lock()

        if tickets > 0 {
            fmt.Println(i+1, "号客人在", num, "买到票", tickets)
            tickets--
        } else {
            fmt.Println(i+1, "号客人", "来晚了，票卖完了")
            mutex.Unlock()
            break
        }
        mutex.Unlock()
    }

}