advent_of_code_2022/day_9/part_1.php

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2022-12-09 16:41:48 +01:00
<?php
$instructions = explode("\n", file_get_contents('./input.txt'));
$h = [0,0];
$t = [0,0];
$places = ["0-0"];
$grid = [
['#'],
];
foreach ($instructions as $instruction) {
[$direction, $length] = explode(' ', $instruction);
for ($i = 0; $i < $length; $i++) {
$newH = $h;
switch ($direction) {
case 'U':
$newH[0]++;
break;
case 'R':
$newH[1]++;
break;
case 'D':
$newH[0]--;
break;
case 'L':
$newH[1]--;
break;
}
if (areTooFarAway($newH, $t)) {
$t = $h;
$places[] = implode('-', $h);
$grid[$h[0]][$h[1]] = '#';
}
$h = $newH;
}
}
displayGrid($grid);
echo count(array_unique($places));
/**
* @param int[] $x
* @param int[] $y
*
* @return bool
*/
function areTooFarAway($x, $y): bool
{
for ($i = $x[0] - 1, $l = $x[0] + 1; $i <= $l; $i++) {
for ($j = $x[1] - 1, $m = $x[1] + 1; $j <= $m; $j++) {
if ($y[0] === $i && $y[1] === $j) {
return false;
}
}
}
return true;
}
/**
* @param array $grid
*
* @return void
*/
function displayGrid($grid): void
{
$maxRow = 0;
foreach ($grid as $item) {
$maxRow = max($maxRow, count($item));
}
$grid = array_reverse($grid);
foreach ($grid as $iValue) {
for ($j = 0; $j <= $maxRow; $j++) {
if (isset($iValue[$j])) {
echo $iValue[$j];
} else {
echo '.';
}
}
echo "\n";
}
}