Determining combination of bits

[Larry Bates]

You didn't say anything about how large the
numbers might get.  If they stay small (e.g. <thousands)
you could just look them up directly from a dictionary.
If they can get arbitrarily large you must use bit
shifing and boolean & (and).

Sounds a lot like a homework assignment, but I'll
give you some "hints".

1) Use bit shifting operator (>>) and boolean &
    operator to isolate each bit in the integer.

2) It will be either zero or one.  Build up a
    list of these which will represent the power
    of two that each one bit represents.

Larry Bates

Sean Berry wrote:
> Say I have a dictionary like the following
> 
> {1:'one',2:'two',4:'three',8:'four',16:'five', etc...}
> 
> and I am given some numbers, say 22, 25, and 9.  I want to determine the 
> keys, powers of 2, that comprise the number.
> 
> Ex.  22 = 16+4+2
>        25 = 16+8+1
>        9   = 8+1
> ...etc...
> 
> How do I get these keys? 
> 
>