public IList <IList <int> > GroupThePeople(int[] groupSizes)
        {
            if (groupSizes.Length < 1 || groupSizes.Length > 500)
            {
                return(null);
            }

            var manager = new GroupManager();

            for (int i = 0; i < groupSizes.Length; i++)
            {
                var newPerson = new Person(i, groupSizes[i]);
                manager.AddPersonToCorrectGroup(newPerson);
            }

            return(manager.GetGroupIds());
        }