31 lines
800 B
PHP
31 lines
800 B
PHP
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<?php
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$grid = array_map(static function ($row) {
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return str_split($row);
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}, explode("\n", file_get_contents('./input.txt')));
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$low_points = [];
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foreach ($grid as $i => $row) {
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foreach ($row as $j => $cell) {
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$count = 0;
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if (!array_key_exists($i - 1, $grid) || $grid[$i - 1][$j] > $cell) {
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$count++;
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}
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if (!array_key_exists($i + 1, $grid) || $grid[$i + 1][$j] > $cell) {
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$count++;
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}
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if (!array_key_exists($j - 1, $row) ||$row[$j - 1] > $cell) {
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$count++;
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}
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if (!array_key_exists($j + 1, $row) || $row[$j + 1] > $cell) {
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$count++;
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}
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if ($count === 4) {
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$low_points[] = (int) $cell;
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}
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}
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}
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echo array_sum($low_points) + count($low_points);
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