2009/4/29 Tim Chase <python.l...@tim.thechases.com>: > Li Wang wrote: >> >> Hi: >> >> If I use an integer to represent bits: >> e.g. 99 represents '1100011' >> >> How can I locate, say the second bit of 99(i.e. '1')? >> >> Although bin(99)[4] could be used to locate it, this transform cost >> too much memory (99 only needs 2Bytes, while string '1100011' needs >> 7Bytes). >> >> Anyone knows how to locate the second bit without using bin() function? > > You mean > > def get_bit(number, bit): > return (number >> bit) & 1 > > ? > Hummm, I have tried this method too, the problem is its time complexity. If the length of my bits is n, then the time complexity is O(n). When I tried to implement this in practice, it did consume a lot of time.
So do you know how could I locate the bit in O(1) time? Transform it into a string is a method, but takes too much space (when I try to process a 2M file, it used more than 100M memory.....). Thank you very much. > -tkc > > > > > -- Li ------ Time is all we have and you may find one day you have less than you think -- http://mail.python.org/mailman/listinfo/python-list
