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#!/usr/bin/env php
<?php
# shamelessly stolen from https://www.geeksforgeeks.org/prime-factor/
// PHP Efficient program to print all
// prime factors of a given number to an arr
// function to print all prime
// factors of a given number n to an arr
function primeFactors($n) {
$n = abs($n);
$f = array();
// Print the number of
// 2s that divide n to the arr
while($n % 2 == 0)
{
$f[] = 2;
$n = $n / 2;
}
// n must be odd at this
// point. So we can skip
// one element (Note i = i +2)
for ($i = 3; $i <= sqrt($n); $i = $i + 2) {
// While i divides n,
// print i and divide n
while ($n % $i == 0)
{
$f[] = $i;
$n = $n / $i;
}
}
// This condition is to
// handle the case when n
// is a prime number greater
// than 2
if ($n > 2)
$f[] = $n;
return $f;
}
$f = array();
for($i = 1; $i <= 100; $i++) { // za vse faktorje v 100!
fprintf(STDERR, "calculating for %d ... ", $i);
$x = primeFactors($i);
fprintf(STDERR, "%s\n", implode(",", $x));
$f = array_merge($f,$x);
}
var_dump($f);
$r = array_count_values($f);
echo "ŠTEVILK 7 JE V 100! natanko ".$r[7]."\n";
?>
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