19 lines
659 B
PHP
19 lines
659 B
PHP
<?php
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$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
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$input = array_map('str_split', $input);
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$o2 = $co2 = $input;
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for ($i = 0; $i < count($input[0]); $i++) {
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if (count($o2) > 1) {
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$bit = (int)(array_sum($column = array_column($o2, $i)) >= ceil(count($column) / 2));
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$o2 = array_filter($o2, fn($line) => $line[$i] == $bit);
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}
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if (count($co2) > 1) {
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$bit = (int) (array_sum($column = array_column($co2, $i)) >= ceil(count($column) / 2));
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$co2 = array_filter($co2, fn ($line) => $line[$i] != $bit);
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}
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}
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echo bindec(implode('', reset($co2))) * bindec(implode('', reset($o2))); //2990784
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