40 lines
807 B
PHP
40 lines
807 B
PHP
<?php
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define('MAX',1000000);
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function is_prime($prime) {
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$sqrt = sqrt($prime);
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for ($i = 3; $i <= $sqrt; $i+=2){
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if ($prime%$i == 0) return false;
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}
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return true;
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}
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function fact($int){
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static $facts = array(1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880);
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return $facts[$int];
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}
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$primes = array(2);
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$primes_ordered = array(2);
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for($i=3;$i<MAX;$i+=2) {
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if(is_prime($i)) {
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//$primes[] = $i;
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$temp = str_split($i);
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sort($temp);
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$primes_ordered[] = implode($temp);
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}
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}
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echo "Found primes below 1mil\n";
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$result = 0;
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foreach($primes_ordered as $p) {
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$counts = fact(strlen($p));
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foreach($primes_ordered as $order) {
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if($p == $order) {
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$counts--;
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}
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}
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if($counts == 0) {
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//echo $p."\n";
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$result++;
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}
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}
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echo $result; |