// Time: O(n) where n is number of bits
// Space: O(1)
public static int GetNext(int n)
{
int temp = n;
int trailingZeros = 0;
int trailingOnesAfterZero = 0;
while (((temp & 1) == 0) && (temp != 0))
{
trailingZeros++;
temp >>= 1;
}
while ((temp & 1) == 1)
{
trailingOnesAfterZero++;
temp >>= 1;
}
if (trailingOnesAfterZero + trailingZeros == 0 ||
trailingOnesAfterZero + trailingZeros == 31)
{
return -1;
}
int rightMostNonTralingZero = trailingOnesAfterZero + trailingZeros;
// Flip rightMostNonTralingZero.
n = BinaryHelpers.SetBit(n, rightMostNonTralingZero);
// Clear all bits below fliped bit.
n &= ~((1 << rightMostNonTralingZero) - 1);
// Add back in number of ones cleared.
n |= (1 << (trailingOnesAfterZero - 1)) - 1;
return n;
}