Merge multiple lists with variable length “popping” elements from each

Question

I\'d like to sort multiple lists (variable number of them) into single list, but keeping the specific order. For example:

List A: { 1,2,3,4,5 }
List B: { 6,7         


        

Answer 1

Shortest and probably slowest solution

int[] A = { 1, 2, 3, 4, 5 };
int[] B = { 6, 7, 8 };
int[] C = { 9, 10, 11, 12 };


var arrs = new[] { A, B, C };
var merged = Enumerable.Range(0, arrs.Max(a => a.Length))
    .Select(x => arrs.Where(a=>a.Length>x).Select(a=>a[x]))
    .SelectMany(x=>x)
    .ToArray();

upd.

Another way to solve - I just refactored @Sinatr answer.

static IEnumerable<T> XYZ<T>(IEnumerable<IList<T>> lists)
{
    if (lists == null)  
        throw new ArgumentNullException();
    var index = 0;

    while (lists.Any(l => l.Count > index))
    {
        foreach (var list in lists)     
            if (list.Count > index)         
                yield return list[index];       
        index++;
    }
}