foo.dart

main() {
  genJobs(int activeWorkers, List<int> numbersOfAlreadyActiveJobs) {

    final maxJobs = 16;
    List<int> jobs = List<int>.generate(maxJobs, (i) => i + 1);
    jobs.removeWhere((item) => numbersOfAlreadyActiveJobs.contains(item));

    final length = jobs.length;

    var partSize = length ~/ activeWorkers;
    if (length != partSize * activeWorkers) {
      partSize++;
    }    

    for (var i = 0; i < activeWorkers; i++) {
      final start = i * partSize;
      var end = start + partSize;
      if (end > length) {
        end = length;
      }

    print(jobs.sublist(start, end));
     
  }

}

  genJobs(8, [7, 8, 3, 4]);
}