On Monday, 25 April 2016 at 15:35:14 UTC, Dominikus Dittes
Scherkl wrote:
On Monday, 25 April 2016 at 15:27:02 UTC, Xinok wrote:
Brute force.
http://dpaste.dzfl.pl/882d7cdc5f74
Yeah. And your test spares the failed case int.min (0x80000000),
because in this case x & -x is negative, but of cause x>>>1 is
positive, so it returns false despite -(2^^31) is in fact a
power of two. So this requires an extra cast to work correct
(in fact no big difference in the assembly):
return (Unsigned!T)(x & -x) > (Unsigned!T)(x >>> 1);
How is it wrong? Negative numbers are NOT powers of two (unless
you have an imaginary/complex exponent), so it's still correct to
return false for -int.min. Should it not?
http://www.wolframalpha.com/input/?i=solve+2^n+%3D+-%282^31%29+for+n
