My PHP solution to Project Euler problem # 2 - http://projecteuler.net/problem=2 - Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... By considering the terms in the Fibonacci sequence whose values do not exceed four m…

project-euler-02-sol-2.php

<?php
$n1 = 1;
$n2 = 1;
$n3 = $n1 + $n2;
$sum = 0;
while($n3 < 4000000) {
	$sum += $n3;
	$n1 = $n2 + $n3;
	$n2 = $n1 + $n3;
	$n3 = $n1 + $n2;
}
echo $sum;
?>

project-euler-02.php

<?php
$n1 = 1;
$n2 = 2;
$sum = 2;
$i = 2;
while($i < 4000000) {
        $i = $n1 + $n2;
        $n1 = $n2;
        $n2 = $i;
        if ($i%2 == 0) {
                $sum += $i;
        }
}
echo $sum;
?>

sol-2 takes 0.00013589859008789 to execute.
original solution takes 0.00013208389282227