8.Trip Length v.1

<?php

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

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


$d['a'] = Distance($x1, $y1, $x2, $y2);
$d['b'] = Distance($x2, $y2, $x3, $y3);
$d['c'] = Distance($x1, $y1, $x3, $y3);

asort($d);
//print_r($d);

$n = array_slice($d,0,2, true);
ksort($n);
$k = array_keys($n);

$sum = $n[$k[0]]+$n[$k[1]];

//print_r($n);
//print_r($k);

if (!array_key_exists('a',$n)){
    echo "1->3->2";
}
if (!array_key_exists('b',$n)){
    echo "2->1->3";
}
if (!array_key_exists('c',$n)){
    echo "1->2->3";
}
echo ": $sum";