Question

I have a set of ranges :

Range1 —- (0-10)

Range2 —- (15-25)

Range3 —- (100-1000) and likewise. I would like to have only the bounds stored since storing large ranges , it would be efficient.

Now I need to search for a number , say 14 . In this case, 14 is not present in any of the ranges whereas (say a number) 16 is present in one of the ranges.

I would need a function

bool search(ranges, searchvalue)
{
if searchvalues present in any of the ranges
return true;
else
return false;
}
How best can this be done ? This is strictly non-overlapping and the important criteria is that the search has to be most efficient.

there is a similar question which I asked considering C++ where we can use map or vector But how can it be best done on C# ?

Answer 1

You can define a class range and do a binary search on it:
it’s better keep list sorted in startup or using sortedlist

    public class Range : IComparable
    {
        public int start;
        public int end;
        public int CompareTo(object obj)
        {
            var result = obj as Range;
            if (result == null)
                return 1;
            if (start > result.start)
                return 1;
            if (result.start >= start && result.end <= end)
                return 0;
            return -1;
        }
    }
    public void findItemInRange(List<Range> ranges, int item)
    {
        // ranges.Sort(); I'll assume list is sorted
        int positionOfItem = ranges.
                            BinarySearch(new Range { start = item, end = item });
    }