On Sat, Apr 7, 2012 at 11:24 AM, Dave <dave_and_da...@juno.com> wrote:
> @Ashgoel: Try this:
>
> bool OnesZerosOnes(unsigned int n)
> {
> if( !(n & 1) || !(n &= n+1) ) return 0;
> n |= n-1;
> return !(n & (n+1));
> }
>
> Here is how it works:
>
> !(n & 1) is true if the number has trailing zeros.
>
> If the number has trailing ones, n &= n+1 replaces the trailing ones with
> zeros.
>
> !(n &= n+1) is true if there are only trailing ones, i.e., the original
> number was zeros followed by ones.
>
> n |= n-1 replaces trailing zeros with ones. Thus, if the original number is
> ones followed by zeros followed by ones, the zeros have been changed to
> ones.
>
> (n & (n+1)) replaces the trailing ones with zeros. If the number is now
> zero, the number is valid, otherwise the number is invalid.
>
> Dave
>
>
Superb, Dave!!
> On Tuesday, April 3, 2012 7:00:36 PM UTC-5, ashgoel wrote:
>>
>> verify that the bits of a number are in format 1s followed by 0s followed
>> by 1s like 1110001 is valid but 100100100 is not
>>
>> Best Regards
>> Ashish Goel
>> "Think positive and find fuel in failure"
>> +919985813081
>> +919966006652
>
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