添加这段代码即可。
public class CommonEqualityComparer<T, V> : IEqualityComparer<T>
???{
??????private Func<T, V> keySelector;
??????public CommonEqualityComparer(Func<T, V> keySelector)
??????{
?????????this.keySelector = keySelector;
??????}
??????public bool Equals(T x, T y)
??????{
?????????return EqualityComparer<V>.Default.Equals(keySelector(x), keySelector(y));
??????}
??????public int GetHashCode(T obj)
??????{
?????????return EqualityComparer<V>.Default.GetHashCode(keySelector(obj));
??????}
???}
???public static class DistinctExtensions
???{
??????public static IEnumerable<T> Distinct<T, V>(this IEnumerable<T> source, Func<T, V> keySelector)
??????{
?????????return source.Distinct(new CommonEqualityComparer<T, V>(keySelector));
??????}
???}