function echoPrimeUpTo($range)
{
echo "Printing prime numbers up tp {$range} <br>";
for ($i = "1"; $i <= $range; $i++) {
if (isPrime($i)) {
echo "{$i}<br>";
}
}
}
function findPrimes($n)
{
$primes = array();
for ($i = 1; $i < $n; $i++) {
if (isPrime($i)) {
$primes[] = $i;
}
}
return $primes;
}
function checkPrimeRange($start, $end)
{
for ($i = $start; $i <= $end; $i++) {
if (isPrime($i)) {
echo "<strong>{$i}, </strong>";
} else {
echo $i . ", ";
}
}
}
function main()
{
$max = 2000000;
$sum = 0;
foreach (range(1, $max) as $number) {
if (isPrime($number)) {
$sum += $number;
}
}
echo $sum;
}
function tPrime($n)
{
$len = strlen($n);
for ($i = 2; $i <= $len; $i++) {
if (isPrime(substr($n, 0, $i)) && isPrime(substr($n, strlen($n) - $i, $i))) {
} else {
return false;
}
}
return true;
}
function countQuadraticConsecutivePrimes($a, $b)
{
$nPrimes = 0;
for ($n = 0; true; ++$n) {
if (isPrime(abs($n * $n + $a * $n + $b))) {
++$nPrimes;
} else {
return $nPrimes;
}
}
}
function Prime($n)
{
$count = 0;
$primeNumber = 0;
for ($k = 1; $count < $n; $k++) {
if (isPrime($k)) {
$count++;
$primeNumber = $k;
}
}
return $primeNumber;
}
function getPrimeNumbers($max)
{
$result = '2';
$nbr = 2;
while ($nbr <= $max) {
if ($nbr % 2 != 0) {
if (isPrime($nbr)) {
$result .= ',' . $nbr;
}
}
$nbr++;
}
return $result;
}
function nextPrime($x)
{
// Precondition: $x is prime or 1. (Handy for initialization of an iterator.)
if ($x == 1) {
return 2;
}
if (isDivisible($x, 2)) {
--$x;
}
do {
$x += 2;
} while (!isPrime($x));
return $x;
}
function main()
{
$n = 10001;
$number = 2;
$i = 0;
while (1) {
if (isPrime($number)) {
$i++;
// echo $i . ' -- '. $number . PHP_EOL;
if ($i === $n) {
echo $number;
break;
}
}
$number++;
}
}
function reducer($num, $sieve, $primes, $target)
{
$negSieve = sieve($num, $primes);
$new = $primes;
foreach ($negSieve as $key => $value) {
if ($value == 0 && isPrime($key, $primes)) {
if (!in_array($key, $primes)) {
$new[] = $key;
if (count($new) - 1 == $target) {
result(104743, $new[$target - 1]);
die;
}
}
}
}
return $new;
}
function factorize($number)
{
$factors = array();
if (isPrime($number)) {
return array($number => 1);
}
$ceil = sqrt($number);
$factor = 2;
while ($factor <= $ceil) {
if ($number % $factor == 0) {
$factors = addFactorizations($factors, factorize($factor));
$factors = addFactorizations($factors, factorize($number / $factor));
break;
}
$factor++;
}
return $factors;
}
function isCircular($num)
{
if (!isPrime($num)) {
return false;
}
if ($num > 10) {
$numstr = (string) $num;
if (strstr($numstr, "0") || strstr($numstr, "5") || strstr($numstr, "2") || strstr($numstr, "4") || strstr($numstr, "6") || strstr($numstr, "8")) {
return false;
}
$len = strlen($numstr);
for ($i = 0; $i < $len - 1; $i++) {
$numstr = (string) $num;
$num = rotateLeft($numstr);
if (!isPrime((int) $num)) {
return false;
}
}
}
return true;
}
function factorize(&$target, &$primes, &$factor)
{
$multiplier = 2;
$factored = true;
$sieve = range($primes[count($primes) - 1] + 1, $factor);
for ($i = 0; $i < count($primes); $i++) {
if ($target % $primes[$i] == 0) {
$target = $target / $primes[$i];
if (isPrime($target)) {
result(6857, $target);
die;
}
}
if ($i == count($primes) - 1) {
$factored = false;
$factor *= $multiplier;
$primes = reducer($factor, $sieve, $primes, $target);
factorize($target, $primes, $factor);
}
}
}
<?php
/**
* 10001st prime
* https://projecteuler.net/problem=7
*/
require '../show_answer.php';
$startTime = microtime(true);
$number = 0;
$value = 2;
$max = 10001;
while ($number < $max) {
if (isPrime($value)) {
$number++;
}
$value++;
}
$result = $value - 1;
showAnswer($result, $startTime);
function isPrime($value)
{
$root = sqrt($value);
$divisor = 2;
while ($divisor <= $root) {
if ($value % $divisor == 0) {
return false;
}
$divisor++;
}
return true;
}
}
return $prime ? true : false;
}
$text = "Hej. Idag är det ";
$text2 = "Tiden är ";
$today = date('Y-m-d');
$time = date("H:i:s");
$hemligSumma = array(10, 20, 30, 40, 50);
$slumpadSida = array('www.flashback.org', 'http://www.piratpartiet.se/', 'www.google.se', 'www.php.net');
echo $text . $today . "<br />" . $text2 . $time . "<br />";
echo "Idag skall vi räkna matematik: ";
if (isset($_POST['submit'])) {
$summa = intval($_POST["ma1"]) + intval($_POST["ma2"]);
echo $_POST["ma1"] . " + " . $_POST["ma2"] . " är lika med " . $summa . "<br /><br />";
if ($summa == $hemligSumma[mt_rand(0, 4)]) {
echo "Du lyckades hitta det hemliga nummret du får en länk <br />" . $slumpadSida[mt_rand(0, 3)];
}
echo isPrime($summa) ? $summa . ' är ett primtal<br/>' : $summa . ' är inte ett primtal<br/>';
}
?>
<form action="<?php
echo $_SERVER['PHP_SELF'];
?>
" method="post">
<input type="text" name="ma1" /> +
<input type="text" name="ma2" /><br />
<input type="submit" name="submit" value="Räkna" />
</form>
</body>
</html>
<?php
function isPrime($num)
{
if ($num == 1) {
return false;
}
if ($num == 2) {
return true;
}
if ($num % 2 == 0) {
return false;
}
for ($i = 3; $i < $num; $i = $i + 2) {
if ($num % $i == 0) {
return false;
}
}
return true;
}
$a = 127;
// для вывода числа
if (isPrime($a)) {
echo "{$a} is a prime";
} else {
echo "{$a} is not a prime";
}
echo "<br>";
var_dump(isPrime(127));
// булевым значением
return false;
}
}
return true;
}
function microtime_float()
{
list($usec, $sec) = explode(" ", microtime());
return (double) $usec + (double) $sec;
}
$start = microtime_float();
$startPrime = microtime_float();
$i = 0;
while ($i < 100000) {
$rand = rand(1147483647, 2147483647);
if (isPrime($rand)) {
echo "+";
} else {
echo "-";
}
$i++;
}
$endPrime = microtime_float();
$startWrite = microtime_float();
$x = 0;
while ($x < 100) {
$i = 0;
$longString = '';
while ($i < 10000) {
$rand = rand();
$longString .= $rand;
return true;
} else {
for ($divisor = 2; $divisor <= (int) sqrt($num); $divisor++) {
if ($num % $divisor == 0) {
return false;
}
}
}
}
return true;
}
if (isset($_POST['submit']) && $_POST['start'] != '' && $_POST['end'] != '' && is_numeric($_POST['start']) && is_numeric($_POST['end'])) {
$start = $_POST['start'];
$end = $_POST['end'];
for ($i = $start; $i <= $end; $i++) {
if (isPrime($i)) {
?>
<strong><?php
echo $i;
?>
</strong>
<?php
} else {
echo $i;
}
if ($i != $end) {
echo ", ";
}
}
}
?>
<?php
require_once '../functions.php';
$num = 2;
$i = 0;
while (true) {
if (isPrime($num)) {
$i++;
}
if ($i == 10001) {
break;
}
$num++;
}
echo $num;
<?php
$fp = fopen("php://stdin", "r");
$testCases = 0;
fscanf($fp, "%d", $testCases);
$n = 0;
while ($testCases-- > 0) {
fscanf($fp, "%d", $n);
echo isPrime($n), "\n";
}
function isPrime($n)
{
if ($n === 1) {
return "Not prime ";
}
for ($i = 2; $i * $i <= $n; ++$i) {
if ($n % $i === 0) {
return "Not prime";
}
}
return "Prime";
}
}
?>
<!DOCTYPE html>
<html>
<head>
<title>Find Primes in Range</title>
</head>
<body>
<form>
<label for="start">Starting Index:</label>
<input type="text" name="start" id="start">
<label for="end">End:</label>
<input type="text" name="end" id="end">
<input type="submit">
</form>
<?php
if (isset($_GET['start']) && isset($_GET['end'])) {
if (is_numeric($_GET['start']) && is_numeric($_GET['end'])) {
for ($i = intval($_GET['start']), $count = 0; $i <= intval($_GET['end']); $i++, $count++) {
$value = isPrime($i) ? "<b>{$i}</b>" : $i;
if ($count != 0) {
echo ', ' . $value;
} else {
echo $value;
}
}
}
}
?>
</body>
</html>
function isPrime($n)
{
// Iterate to half of the supplied number, rounded up if necessary. I can't use the square root like I had originally planned.
for ($i = 3; $i <= ceil($n / 2); $i++) {
if ($n % $i == 0) {
return false;
}
}
return true;
}
$a = 600851475143;
//$a = 13195;
for ($i = 3; $i <= floor($a / 2); $i = $i + 2) {
if ($a % $i == 0) {
$y = $a / $i;
if (isPrime($y)) {
echo $y . '<br>';
break;
}
}
}
//
//
//// Script end
//function rutime( $ru, $rus, $index ) {
// return ( $ru["ru_$index.tv_sec"] * 1000 + intval( $ru["ru_$index.tv_usec"] / 1000 ) )
// - ( $rus["ru_$index.tv_sec"] * 1000 + intval( $rus["ru_$index.tv_usec"] / 1000 ) );
//}
//
//$ru = getrusage();
//echo "This process used " . rutime( $ru, $rustart, "utime" ) .
#echo $n."<br>";
return $n * factorial($n - 1);
} else {
return 1;
}
}
echo "factorial(5) = " . factorial(5) . "<br><br>";
#10번
echo "<h3>10.</h3>";
function isPrime($num)
{
if ($num % 2 == 1) {
# 1 3 5 7 9 11 13 15 17 19 21 23 25 ... 홀수
if ($num % 3 != 0 && $num % 5 != 0) {
echo "This is prime number!!<br>";
}
} else {
echo "This is not prime number...<br>";
}
}
$num1 = 2;
$num2 = 13;
echo "INPUT >> {$num1}<br>";
isPrime(2);
echo "INPUT >> {$num2}<br>";
isPrime(13);
echo "<br><br>";
?>
</body>
</html>
<div class="page-header">
<h1>Solution</h1>
</div>
<form class="form-horizontal" action="index2.php" method="POST">
<div class="form-group">
<label for="number" class="col-sm-2 control-label">Enter a number</label>
<div class="col-sm-10">
<input type="number" class="form-control" name="given_number" id="number" placeholder="Enter an Integer number....">
</div>
</div>
<div class="form-group">
<label for="result" class="col-sm-2 control-label">Result</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="result" value="<?php
if (isset($_POST['given_number'])) {
echo isPrime($_POST['given_number']);
}
?>
">
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<button type="submit" class="btn btn-default" name="btn" value="submit">Submit</button>
</div>
</div>
</form>
<div class="panel panel-success">
<div class="panel-heading">
<h3 class="panel-title">Solution Code</h3>
</div>
What is the largest prime factor of the number 600851475143 ?
Solution by Tom Tillistrand
Solved for 13892 instead of 600851475143 because browser cannot handle larger number.
*/
$number = 13892;
$index = ceil($number / 2);
// The largest possible factor of any number is half of it, so we start our index here
$primeFound = false;
// Flag variable set to false initially. When prime factor is found, it's set to true to stop the loop
function isPrime($testNum)
{
for ($i = 2; $i <= $testNum / 2; $i++) {
if ($testNum % $i === 0) {
return false;
}
}
return true;
}
while (!$primeFound) {
if ($number % $index === 0) {
if (isPrime($index)) {
echo "<p>The largest prime factor of 13892 is {$index}";
$primeFound === true;
break;
}
}
$index--;
}
?>
</body>
</html>
<input type="text" id="startIndex" name="start"/>
<label for="endIndex">End: </label>
<input type="text" id="endIndex" name="end"/>
<input type="submit" value="Submit"/>
</form>
<p>
<?php
for ($i = $start; $i <= $end; $i++) {
?>
<?php
if (isPrime($i)) {
?>
<strong><?php
echo $i;
?>
</strong><?php
}
if (!isPrime($i)) {
echo $i;
}
if ($i < $end) {
?>
, <?php
}
?>
<?php
}
?>
</p>
</body>
</html>
}
}
return true;
}
$primeNumbers = array();
for ($i = 1; $i <= 10000; $i++) {
if (isPrime($i)) {
array_push($primeNumbers, $i);
}
}
$twiceSquares = array();
for ($i = 1; $i <= 10000; $i++) {
array_push($twiceSquares, 2 * pow($i, 2));
}
for ($n = 35; $n <= 10000; $n += 2) {
if (!isPrime($n)) {
foreach ($twiceSquares as $sq) {
if ($sq >= $n) {
break;
}
foreach ($primeNumbers as $prime) {
if ($prime >= $n) {
break;
}
if ($prime + $sq == $n) {
continue 3;
}
}
}
echo $n;
break;
}
if ($num == 2) {
return true;
}
if ($num % 2 == 0) {
return false;
}
for ($i = 3; $i <= ceil(sqrt($num)); $i = $i + 2) {
if ($num % $i == 0) {
return false;
}
}
return true;
}
for ($i = $startIndex; $i <= $endIndex; $i++) {
$isPrime = isPrime($i);
if ($isPrime === true) {
if ($i == $endIndex) {
?>
<b><?php
echo "{$i}";
?>
</b>
<?php
} else {
?>
<b><?php
echo "{$i}, ";
?>
</b>
<?php
} else {
for ($i = 2; $i <= (int) sqrt($number); $i++) {
if ($number % $i == 0 && $i != $number) {
$checker = false;
break;
} else {
$checker = true;
}
}
}
if ($checker) {
return "<span style='font-weight: bold'>{$number}</span>";
} else {
return "<span>{$number}</span> ";
}
}
if (isset($_GET['start'], $_GET['end'])) {
$startIndex = $_GET['start'];
$endIndex = $_GET['end'];
if (is_numeric($startIndex) && is_numeric($endIndex) && $endIndex > $startIndex) {
for ($i = $startIndex; $i <= $endIndex; $i++) {
if ($i == $endIndex) {
echo isPrime($i);
} else {
echo isPrime($i) . ", ";
}
}
} else {
die('Please enter valid numbers!');
}
}