def __init__(self, num_disks, number=None):
self.disks = list()
self.disks_by_name = dict()
self.disk_names = list()
disk_names = ["orange", "yellow", "green", "blue", "purple"]
for idx in range(num_disks):
disk = Disk()
disk_name = disk_names[idx]
self.disks.append(disk)
self.disks_by_name[disk_names[idx]] = disk
self.disk_names.append(disk_name)
if number is not None:
pos = self.num_disk_positions
rest = number
for disk_name in reversed(disk_names):
disk = self.disks_by_name[disk_name]
disk_idx = disk_names.index(disk_name)
pole_idx = rest // pos**disk_idx
disk.pole = pole_idx
rest = rest - pole_idx * pos**disk_idx
