Richard Heathfield <rjh@cpax.org.uk> wrote:
On 22/03/2025 08:07, Peter 'Shaggy' Haywood wrote:
<snip>
Here's my solution, for what it's worth:
#include <stdio.h>
unsigned long weird(unsigned long n)
{
printf("%lu", n);
if(n & 1)
{
/* Odd - multiply by 3 & add 1. */
n = n * 3 + 1;
Or you can save yourself a multiplication
n = (n << 2) - (n - 1);
potentially shaving entire picoseconds off the runtime.
}
else
{
/* Even - divide by 2. */
n /= 2;
do
{
n >>= 1;
} while(~(n & 1));
...and there goes another attosecond.
| Date | Sujet | # | Auteur | |
| 20 Apr 26 |  … |
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