// function to work out the km travelled of a reindeer after n seconds
function distanceAfter($d, $s)
{
// work out length of go/rest cycle
$cycle = $d['duration'] + $d['rest'];
// distance - full cycles
$distance = floor($s / $cycle) * $d['speed'] * $d['duration'];
// distance - remaining part cycle
$distance += min($s % $cycle, $d['duration']) * $d['speed'];
return intval($distance);
}
// work out who is in front each second
for ($i = 1; $i <= 2503; $i++) {
// loop reindeer and work out how far each has travelled
foreach ($deer as $name => $d) {
$deer[$name]['distance'] = distanceAfter($d, $i);
}
// award a point to whoever is in the lead
$furthest = 0;
foreach ($deer as $name => $d) {
if ($d['distance'] > $furthest) {
$furthest = $d['distance'];
$fastBastards = array($name);
} elseif ($d['distance'] == $furthest) {
$fastBastards[] = $name;
}
}
// add point(s)
foreach ($fastBastards as $jimmySpeedyPants) {
$deer[$jimmySpeedyPants]['score']++;
}
*/
// parse the input file into an array
$deer = array();
foreach (file('input/day-14.txt') as $line) {
preg_match('/^(\\w+) can fly (\\d+) km\\/s for (\\d+) seconds, but then must rest for (\\d+) seconds\\.$/', $line, $m);
$deer[$m[1]] = array('speed' => $m[2], 'duration' => $m[3], 'rest' => $m[4]);
}
// function to work out the km travelled of a reindeer after n seconds
function distanceAfter($d, $s)
{
// work out length of go/rest cycle
$cycle = $d['duration'] + $d['rest'];
// distance - full cycles
$distance = floor($s / $cycle) * $d['speed'] * $d['duration'];
// distance - remaining part cycle
$distance += min($s % $cycle, $d['duration']) * $d['speed'];
return intval($distance);
}
// loop reindeer and work out how far each has travelled
foreach ($deer as $name => $d) {
$deer[$name]['distance'] = distanceAfter($d, 2503);
}
// find the winner
$furthest = 0;
foreach ($deer as $d) {
if ($d['distance'] > $furthest) {
$furthest = $d['distance'];
}
}
// output answer
echo 'Answer: ' . $furthest;