HackerRank utils

Utils.cs

using System.Linq;
public static class U { 
    public static string Join<T>(this IEnumerable<T> rg, string sep = " ") => string.Join(sep, rg.Select(o => o.ToString()));
    public static int ReadInt() => int.Parse(Console.ReadLine());
    public static IEnumerable<int> ParseInts() => Console.ReadLine().Split(' ').Select(int.Parse);
    public static int[] ReadInts() => ParseInts().ToArray();
    public static IEnumerable<long> ParseLongs() => Console.ReadLine().Split(' ').Select(long.Parse);
    public static long[] ReadLongs() => ParseLongs().ToArray();
    public static IEnumerable<T> Order<T>(this IEnumerable<T> @this) where T : IComparable<T> => @this.OrderBy((T t) => t);
    public static IEnumerable<T> OrderDescending<T>(this IEnumerable<T> @this) where T : IComparable<T> => @this.OrderByDescending((T t) => t);
    public static void Swap<T>(ref T lhs, ref T rhs) { T temp; temp = lhs; lhs = rhs; rhs = temp; }
    public static bool All(this IEnumerable<bool> @this) => @this.All(b=>b);
    public static bool Any(this IEnumerable<bool> @this) => @this.Any(b=>b);
     
    public static bool NextPermutation<T>(this T[] a) where T: IComparable
    {
        int k = a.Length - 2;
        while (k >= 0 && a[k].CompareTo(a[k+1])>=0) k--;
        if(k<0) return false;
        int l = a.Length - 1;
        while (l > k && a[l].CompareTo(a[k]) <= 0) l--;
        U.Swap(ref a[k], ref a[l]);
        for (int i = k + 1, j = a.Length - 1; i < j; i++,j--)
            U.Swap(ref a[i], ref a[j]);
        return true;
    }
}