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Wednesday, May 31, 2006

A couple of solutions...

def isPowerOf2(num):

  return num == 1 or num == 2 or (num%2 == 0 and isPowerOf2(num/2))

def isPowerOf2(num):

  count = 0

  while(num > 0):

    count += num%2

    num >>= 1

  return count == 1

Update: From David, in the comments:

def isPowerOf2(num):

  return (num & (num - 1) == 0)

I've never gotten to do enough bit twiddling to have let me think of that.

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Permalink | 2 Comments | Tags: Code | id 8084

23:10 (utc-5)
edited: 2006-06-01 11:22 (utc-5)

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Comments

David Lindquist (http://www.stringify.com/) wrote:

Howza bout:

def isPowerOf2(num):

    return (num & (num - 1) == 0)

∴ David Lindquist | 1-Jun-2006 12:14am est | http://www.stringify.com/ | #9477

Keith (http://keithdevens.com/) wrote:

See, there you go. I suck at bit twiddling. Thanks!

∴ Keith | 1-Jun-2006 9:32am est | http://keithdevens.com/ | #9478

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