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This commit is contained in:
Daniil Gentili 2016-06-25 20:39:49 +02:00
parent f518034af0
commit 3b4b6d5362
2 changed files with 11 additions and 3 deletions

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@ -14,7 +14,15 @@ function everynth($array, $n) {
}
return $result;
}
function array_merge_ignore_keys($array1, $array2) {
if(count($array1) == count($array2)) {
$i = -1;
foreach ($array1 as $key => $val){
$array1[$key] = $array2[$i++];
}
} else return null;
return $array1;
}
function primesbelow($N) {
$correction = (($N % 6) > 1);
$N = [0 => $N, 1 => ($N - 1), 2 => ($N + 4), 3 => ($N + 3), 4 => ($N + 2), 5 => ($N + 1) ][($N % 6) ];
@ -23,8 +31,8 @@ function primesbelow($N) {
foreach (pyjslib_range(((pyjslib_int(pow($N, 0.5)) / 3) + 1)) as $i) {
if ($sieve[$i]) {
$k = ((3 * $i) + 1) | 1;
$sieve = array_merge($sieve, array_merge(everynth(array_splice($sieve, floor($k*$k / 3)), 2*$k), ([false] * ((((($N / 6) - (($k * $k) / 6)) - 1) / $k) + 1))));
$sieve = array_merge($sieve, array_merge(everynth(array_splice($sieve, floor((k*k + 4*k - 2*k*(i%2)) / 3)), 2*$k), ([false] * ((((($N / 6) - (((($k * $k) + (4 * $k)) - ((2 * $k) * ($i % 2))) / 6)) - 1) / $k) + 1))));
$sieve = array_merge($sieve, array_merge_ignore_keys(everynth(array_splice($sieve, floor($k*$k / 3)), 2*$k), ([false] * ((((($N / 6) - (($k * $k) / 6)) - 1) / $k) + 1))));
$sieve = array_merge($sieve, array_merge_ignore_keys(everynth(array_splice($sieve, floor((k*k + 4*k - 2*k*(i%2)) / 3)), 2*$k), ([false] * ((((($N / 6) - (((($k * $k) + (4 * $k)) - ((2 * $k) * ($i % 2))) / 6)) - 1) / $k) + 1))));
}
}
return ([2, 3] + array_map(function ($i, $sieve) { if($sieve[$i]) return (3 * $i + 1) | 1; }, pyjslib_range(1, (($N / 3) - $correction)), $sieve));