We consider one item after the other and if the current item fits into the current bin. Then we put the item into the bin, otherwise we get a new bin and we put the item into this new bin.
You have to think like if we have bins that come from right to left and we have one current bin and when we get a item we see if this item can fit into the current bin. If it can fit then we put it into the bin, otherwise we move the bin on the left and we take from the right another bin and we put the item into this bin.
