Kotlin:如何利用Kotlin数据结构在面试中编写有效的解决方案

Question

我在一次面试中问到了这个问题，在最后一节我和科特林乐队的谈话中失败了。我正在尝试重新创建fun taskCompleted() --我想看看如何实现它，仅仅是为了玩它。所以这就是我所得到的

data class Article(val title: String, val content: String, val duration: Int, val date: Int)

data class StreakInfo(val goalsMet: Int, val breakDown: List<Boolean>)

interface ReadingGoalService{
    fun getDailyReadingGoal(): Int
}

interface TaskService{

    fun allTasks(): List<Article>
}

class MockInterview{

   
    fun taskCompleted(){}

    //temporary
    private fun today(): Int{

        return 1
    }
}

fun getAllSteaks(streakInfo: StreakInfo){
    //don't implement
}

我的要求是在哪里做fun taskCompleted()，我应该做以下几件事

        //TODO 1 current day is today
        //TODO 2 take all the articles that were read on the current day
        //TODO 3 sum readingDurations of articles for current Day
        //TODO 4 check if sum of readingDurations is >= than reading goal
        // TODO 5 if sum of readingDuration is >= goal repeat 2..3.. and 4. for currentDay-1
        //TODO 6 if sum of readingDuration is < goal - stop

知道我怎么能在科特林做到这一点吗？我计划将此作为一个学习过程。

Answer 1

正如我所提到的，我强烈建议您看看Kotlin Koans，因为他们向您介绍了许多我认为肯定会教您如何执行几乎所有那些TODO的例子！(他们有解决办法！)

在这次采访中，您是否知道如何使用Kotlin标准库中的聚合和映射函数，并检查是否可以通过使用适当数量的参数来重用大量代码。

以下是我如何处理这个问题：

fun today() = 1 // TODO 1: Current day is today

fun tasksDoneByDay(taskService: TaskService, day: Int = today()): List<Article> {
    // TODO2: Here I have all tasks that were done at "today()"
    return taskService.allTasks().filter { task -> task.date == day }
}

// TODO 3
fun durationsForDay(taskService: TaskService, day: Int = today()) = tasksDoneByDay(taskService, day).sumBy { it.duration }


// TODO 4
fun durationsForDayMeetGoal(taskService: TaskService, goal: Int, day: Int = today()) = durationsForDay(taskService, day) >= goal

// TODO 5 if sum of readingDuration is >= goal repeat 2..3.. and 4. for currentDay-1

fun todo5(taskService: TaskService, goal: Int) {
  val today = today()
  return when(val durationsForTodayMeetGoal = durationsForDayMeetGoal(taskService, goal, today)) {
    false -> durationsForDayMeetGoal(taskService, goal, today - 1)
    true -> durationsForTodayMeetGoal
  }
}

// TODO 6 I don't understand...

essentially the same as todo five but when it's false dont do anything?