Arrange 0's & 1's in a array

Question

This is one of an interview question which I had recently. I would like to know others perception of approach for this problem.

Question:

Yo

Answer 1

What the heck, here is the whole solution: arr is list of items, item.id is 0 or 1, stored as int.
This code moves the 0s to the front.

count = { 0:0, 1:len(arr)/2 }
for ii in range(len( arr )):
  id = arr[ii].id
  arr[ii].id = count[id]
  count[id] += 1
for ii in range(len( arr )):
  while arr[ii].id != ii:
    T = arr[ii]
    arr[ii] = arr[arr[ii].id]
    arr[T.id] = T
for ii in range(len( arr )):
  arr[ii].id = (ii >= len(arr)/2)