AdventOfCode/AdventOfCode.HelperClasses/IntegerRange.cs

using System.Collections;

namespace AdventOfCode.HelperClasses;

public record IntegerRange(long start, long end) : IEnumerable<long>
{
    public long Count => end - start + 1;

    public bool Contains(long number) => start <= number && end >= number;

    public bool TryCombine(IntegerRange other, out IntegerRange combined)
    {
        if (Contains(other.start) || other.start == end + 1)
        {
            var isEndInRange = Contains(other.end);
            combined = isEndInRange ? this : this with {end = other.end};
            return true;
        }
        
        if (other.Contains(start) || start == other.end + 1)
        {
            var isEndInRange = other.Contains(end);
            combined = isEndInRange ? other : other with {end = end};
            return true;
        }

        combined = this;
        return false;
    }

    public IEnumerator<long> GetEnumerator() => new IntegerRangeEnumerator(start, end);

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}

public record IntegerRangeEnumerator(long start, long end) : IEnumerator<long>
{
    private long _current = start - 1;

    public bool MoveNext()
    {
        if(_current >= end) return false;
        _current++;
        return true;
    }

    public void Reset()
    {
        _current = start - 1;
    }

    long IEnumerator<long>.Current => _current;

    object? IEnumerator.Current => _current;

    public void Dispose()
    {
        GC.SuppressFinalize(this);
    }
}