How to get a range of numbers

Question

I have a number span [1, 20].

I need a method that returns me the range of available numbers if I decide to prohibit the range [15, 18]. My method should return me a list containing [1,15] and [18, 20]

A Range object might look something like this.

public class Range { int Start {get;set;} int End {get;set;} } 

Any help would be appreciated.

Answer 1

You need to go through the forbidden ranges and iteratively create valid ranges in this case.

 public List<Range> getValidRanges(Range total, List<Range> banned) { List<Range> valid = new ArrayList<Range>(); int start = total.getStartTime(); for(Range range: banned) { valid.add(new Range(start,banned.getStart())); start = banned.getEnd(); } valid.add(new Range(start,total.getEnd())); return valid; } 

Answer 2

How about this?

 IEnumerable<int> range = Enumerable.Range(1, 20); IEnumerable<int> banned = Enumerable.Range(15, 4); return range.Except(banned); 

The Enumerable class already has a static method that returns a range of values ​​for you - it would be easier to just use these semantics.

Answer 3

This is one way:

 static void Main(string[] args) { int[] allNumbers = Enumerable.Range(1, 20).ToArray(); GetNumbers(ref allNumbers, new int[] { 16, 17 }); } private static void GetNumbers(ref int[] nums, int[]exclude) { List<int> numsToExlucde =new List<int>(); numsToExlucde.InsertRange(0, exclude); nums = nums.Where(w => !numsToExlucde.Contains(w)).ToArray(); } 

Answer 4

You have four possible cases. The method might look like this (I assume that the range contains only integers):

 public class Range { public int Start { get; set; } public int End { get; set; } public IList<Range> Exclude(Range r) { if (r.Start <= Start && r.End < End) { return new List<Range>{new Range { Start = r.End + 1, End = End }}; } else if (r.Start > Start && r.End >= End) { return new List<Range>{new Range { Start = Start, End = r.Start - 1 }}; } else if (r.Start > Start && r.End < End) { return new List<Range> { new Range { Start = Start, End = r.Start - 1 }, new Range { Start = r.End + 1, End = End } }; } return new List<Range>(); } } // ... static void Main(string[] args) { Range r = new Range { Start = 1, End = 20}; var list = r.Exclude(new Range{ Start = 1, End = 2} ); } 

Answer 5

This can help you remove a range from another or from a set of ranges:

 public class Range { public int Start { get; private set; } public int End { get; private set; } public Range(int start, int end) { Start = start; End = end; } public IEnumerable<Range> RemoveFrom(Range range) { return RemoveFrom(new Range[] { range }); } public IEnumerable<Range> RemoveFrom(IEnumerable<Range> items) { foreach (Range item in items) { if (End >= item.Start && Start <= item.End) { if (item.Start <= Start) { yield return new Range(item.Start, Start); } if (item.End >= End) { yield return new Range(End, item.End); } } else { yield return item; } } } } 

Example:

 Range range = new Range(1, 20); foreach (Range r in new Range(15,18).RemoveFrom(range)) { Console.WriteLine("{0} - {1}", r.Start, r.End); } 

Conclusion:

 1 - 15 18 - 20 

An example of removing multiple ranges from other ranges:

 Range[] items = new Range[] { new Range(1, 100), new Range(200, 300) }; Range[] exclude = new Range[] { new Range(25, 75), new Range(250, 280), new Range(90, 210) }; foreach (Range r in exclude) { items = r.RemoveFrom(items).ToArray(); } foreach (Range r in items) { Console.WriteLine("{0} - {1}", r.Start, r.End); } 

Conclusion:

 1 - 25 75 - 90 210 - 250 280 - 300