42 lines
955 B
PHP
42 lines
955 B
PHP
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<?php
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function isPrimary($number){
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$i=1;
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while(getPrimeNumber($i) <= sqrt($number)){
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if(fmod($i,getPrimeNumber($i))==0){
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return false;
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}
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$i=$i+2;
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}
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return true;
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}
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function getPrimeNumber($order){
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static $primeNumbersList=array(2,3);
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//if already finded:
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if(isset($primeNumbersList[$order-1])){
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return $primeNumbersList[$order-1];
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}
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$i=$primeNumbersList[count($primeNumbersList)-1] + 2;
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while (count($primeNumbersList) < $order){
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$isPrimaryNumber=true;
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foreach($primeNumbersList as $pr){
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if($pr>sqrt($i)){
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break;
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}
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if(fmod($i,$pr)==0){
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$isPrimaryNumber=false;
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break;
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}
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}
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if($isPrimaryNumber){
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$primeNumbersList[]=$i;
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}
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$i=$i+2;//sert à rien de tester les nombres pairs
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}
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return $i-2;
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}
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