127 lines
2.7 KiB
PHP
127 lines
2.7 KiB
PHP
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<?php
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$input_file = '../inputs/day11.txt';
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if (file_exists($input_file)) {
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$input = file_get_contents($input_file);
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if ($input != null) {
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$rows = array_map('trim', explode("\n", $input));
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print 'Part 1 answer: ' . solve($rows, false) . "\n";
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print 'Part 2 answer: ' . solve($rows, true) . "\n";
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}
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}
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function solve(array $rows, bool $moreTolerant): int
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{
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$changed = true;
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$occupied = 0;
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$newState = $rows;
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while ($changed) {
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$simulation_result = simulate($newState, $moreTolerant);
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$changed = $simulation_result->changed;
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$occupied = $simulation_result->full;
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$newState = $simulation_result->state;
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}
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return $occupied;
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}
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function simulate(array $rows, bool $moreTolerant): day11_state
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{
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$newState = $rows;
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$changed = false;
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$empty = 0;
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$floor = 0;
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$full = 0;
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for ($i = 0; $i < count($rows); $i++) {
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for ($j = 0; $j < strlen($rows[$i]); $j++) {
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$adjacent_occupied = get_adjacent_occupied($moreTolerant, $rows, $i, $j);
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if ($rows[$i][$j] === 'L' && $adjacent_occupied === 0) {
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$changed = true;
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$full += 1;
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$newState[$i][$j] = '#';
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} elseif ($rows[$i][$j] === '#' && $adjacent_occupied >= ($moreTolerant ? 5 : 4)) {
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$changed = true;
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$empty += 1;
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$newState[$i][$j] = 'L';
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} else {
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if ($rows[$i][$j] === 'L')
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$empty += 1;
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elseif ($rows[$i][$j] === '#')
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$full += 1;
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else
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$floor += 1;
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}
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}
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}
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return new day11_state($newState, $changed, $empty, $floor, $full);
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}
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function get_adjacent_occupied(bool $moreTolerant, array $state, int $y, int $x): int
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{
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$occupied = 0;
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if ($moreTolerant === false) {
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for ($i = $y - 1; $i < $y + 2; $i++) {
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if ($i >= 0 && $i < count($state)) {
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for ($j = $x - 1; $j < $x + 2; $j++) {
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if ($j >= 0 && $j < strlen($state[$i]) && !($i === $y && $j === $x)) {
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$occupied += $state[$i][$j] === '#' ? 1 : 0;
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}
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}
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}
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}
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} else {
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$x_dir = -1;
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$y_dir = -1;
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while (true) {
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$x_pos = $x;
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$y_pos = $y;
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while (true) {
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if ($x_dir === 0 && $y_dir === 0)
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break;
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$x_pos += $x_dir;
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$y_pos += $y_dir;
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if ($y_pos < 0 || $y_pos >= count($state) || $x_pos < 0 || $x_pos >= strlen($state[$y_pos]))
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break;
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elseif ($state[$y_pos][$x_pos] === '.')
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continue;
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else {
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$occupied += $state[$y_pos][$x_pos] === '#';
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break;
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}
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}
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$y_dir += 1;
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if ($y_dir == 2) {
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$y_dir = -1;
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$x_dir += 1;
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}
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if ($x_dir == 2)
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break;
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}
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}
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return $occupied;
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}
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class day11_state
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{
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public array $state;
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public bool $changed;
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public int $empty;
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public int $floor;
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public int $full;
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function __construct(array $state, bool $changed, int $empty, int $floor, int $full)
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{
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$this->state = $state;
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$this->changed = $changed;
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$this->empty = $empty;
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$this->floor = $floor;
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$this->full = $full;
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}
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}
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