8.Trip Length v.3

<?php

function Distance($x1, $y1, $x2=0, $y2=0)
{
    return sqrt(pow($x1 - $x2, 2) + pow($y1 - $y2, 2));
}

list($x1, $y1, $x2, $y2, $x3, $y3) = explode(", ", trim(fgets(STDIN)));

$d3 = Distance($x1, $y1, $x2, $y2);
$d1 = Distance($x2, $y2, $x3, $y3);
$d2 = Distance($x1, $y1, $x3, $y3);

$trip1 = $d1 + $d3;
$trip2 = $d1 + $d2;
$trip3 = $d2 + $d3;

if ($trip3 < $trip2 && $trip3 < $trip1) {
    echo "2->1->3: " . $trip3;
} elseif ($trip2 < $trip1) {
    echo "1->3->2: " . $trip2;
} else {
    echo "1->2->3: " . $trip1;
}