Range data structure (integer sequence with start, stop, step parameters)

Supports negative interval and negative step

Provides the following operations:

• Enumeration
• Access element by index optimized to O(1) time/space
• bool Contains(int number) optimized to O(1) time/space
• int IndexOf(int number) optimized to O(1) time/space

Example:

var range = new Range(10);

foreach(int el in range)
	Console.Write(el + " "); // 0 1 2 3 4 5 6 7 8 9

Console.WriteLine(range.Sum); // 45

var negRange = new Range(5, -20, -3); // 5, 2, -1,... -19
Console.WriteLine(negRange.Count); // 9

Console.WriteLine( negRange.Contains(-4) ); // True

Console.WriteLine( negRange[5] ); // -10

var bigRange = new Range(-567656, 234543234, 27);

Console.WriteLine(bigRange.IndexOf(397378)); // 35742