/// <param name="n">0 ~ source.Length - 1</param>
public static ItemWithIndex <T> NthSmallest <T>(this ReadOnlySpan <T> source, int n) where T : IComparable <T>
{
var pool = ArrayPool <int> .Shared.Rent(source.Length);
try
{
var indices = pool.AsSpan(0, source.Length);
QuickSelect.Iota(indices);
QuickSelect.Execute(source, indices, n);
return(new ItemWithIndex <T>(source[indices[n]], indices[n]));
}
finally
{
ArrayPool <int> .Shared.Return(pool);
}
}
/// <param name="n">0 ~ source.Count - 1</param>
public static ItemWithIndex <T> NthSmallest <T>(this IReadOnlyList <T> source, int n, Comparer <T> comparer)
{
var pool = ArrayPool <int> .Shared.Rent(source.Count);
try
{
var indices = pool.AsSpan(0, source.Count);
QuickSelect.Iota(indices);
QuickSelect.Execute(source, indices, n, comparer);
return(new ItemWithIndex <T>(source[indices[n]], indices[n]));
}
finally
{
ArrayPool <int> .Shared.Return(pool);
}
}
