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Is_Prime.php
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Is_Prime.php
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<?php
/**
* Is Prime (Simple Version)
*
* Time Complexity: O(sqrt(n))
*/
function isPrime($n) {
if ($n <= 1)
return false;
elseif ($n <= 3)
return true;
elseif ($n % 2 == 0 || $n % 3 == 0)
return false;
$i = 5;
while ($i * $i <= $n) {
if ($n % $i == 0 || $n % ($i + 2) == 0)
return false;
$i += 6;
}
return true;
}
// ----------------
// --- Examples ---
// ----------------
define("NL", PHP_SAPI === 'cli' ? "\n" : "<br />"); // define new line feed based on web/cli
$n = 62;
printf("isPrime(%d) = %s" . NL, $n, (isPrime($n)) ? 'Yes' : 'No' );
$n = 563;
printf("isPrime(%d) = %s" . NL, $n, (isPrime($n)) ? 'Yes' : 'No' );
$n = 4789;
printf("isPrime(%d) = %s" . NL, $n, (isPrime($n)) ? 'Yes' : 'No' );
$n = 99991;
printf("isPrime(%d) = %s" . NL, $n, (isPrime($n)) ? 'Yes' : 'No' );
$n = 107863;
printf("isPrime(%d) = %s" . NL, $n, (isPrime($n)) ? 'Yes' : 'No' );