优雅而高效的linq解决方案来计算剧集的数量

Question

我有几个这样的类:

public class TvShow
{
    public Title {get; set;}
    public List<Season> Seasons {get; set;}
}
public class Season
{
    public int SeasonNumber {get; set;}
    public List<Episode> Episodes {get; set;}
}
public class Episode
{
    public int EpisodeNumber {get; set;}
}

我有一个电视节目列表，我想以一种有效的方式获得所有电视节目所有季节的总集数。显然有两个解决方案:

int count = 0;
foreach (var show in tvShows) {
    foreach (var season in show.Seasons {
        foreach (var episode in season.Episodes {
            count++;
        }
    }
}

我可以用linq做什么更优雅或更快的事情吗?

Answer 1

好吧，你的代码相当于:

int count = tvShows.SelectMany(show => show.Seasons)
                   .SelectMany(season => season.Episodes)
                   .Count();

或者你可以使用Sum找出每个节目有多少集，然后再找出所有节目的总集数:

int count = tvShows.Sum(show => show.Seasons.Sum(season => season.Episodes.Count));

或者是一种混合，只是把所有剧集的所有季节的剧集数加起来:

int count = tvShows.SelectMany(show => show.Seasons)
                   .Sum(season => season.Episodes.Count);

我希望最后一个是最有效的，但实际上，除非你有很多节目，我希望所有的选择都非常快。最后一个也很优雅，所以这就是我想要的

Answer 2

类似

tvShows.SelectMany(show => show.Seasons)
       .Sum(season => season.Episodes.Count)