go面试题：第一天

func main() {
    m := map[string]int{
        "G": 7, "A": 1,
        "C": 3, "E": 5,
        "D": 4, "B": 2,
        "F": 6, "I": 9,
        "H": 8,
    }
    var order []string
    for k, _ := range m {
        order = append(order, k)
    }
    fmt.Println(order)
}

type UserAges struct {
    ages map[string]int
    sync.Mutex
}

func (ua *UserAges) Add(name string, age int) {
    ua.Lock()
    defer ua.Unlock()
    ua.ages[name] = age
}

func (ua *UserAges) Get(name string) int {
    if age, ok := ua.ages[name]; ok {
        return age
    }
    return -1
}

func main() {
    count := 1000
    gw := sync.WaitGroup{}
    gw.Add(count * 3)
    u := UserAges{ages: map[string]int{}}
    add := func(i int) {
        u.Add(fmt.Sprintf("user_%d", i), i)
        gw.Done()
    }
    for i := 0; i < count; i++ {
        go add(i)
        go add(i)
    }
    for i := 0; i < count; i++ {
        go func(i int) {
            defer gw.Done()
            u.Get(fmt.Sprintf("user_%d", i))
        }(i)
    }
    gw.Wait()
    fmt.Println("Done")
}