lAssume that the
number of data elements is comparable to,
or larger than, the number of buckets.
lGo through the data
once, putting each element in the
corresponding list.
This is
O(n).
lConcatenate
the resulting lists.
This is also
O(n).
lTherefore we have
O(n) overall.
lRemember that
bucket sorting makes special assumptions
about the data.