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<?php |
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declare(strict_types=1); |
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namespace leetcode; |
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class MaximalSquare |
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{ |
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public static function maximalSquare(array $matrix): int |
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{ |
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[$m, $n, $ans] = [count($matrix), count($matrix[0]), 0]; |
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if ($m <= 0 || $n <= 0) { |
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return $ans; |
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} |
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$helper = static function (array $array, int $k) { |
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$n = count($array); |
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if ($n < $k) { |
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return 0; |
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} |
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$counter = 0; |
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for ($i = 0; $i < $n; $i++) { |
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$counter = $array[$i] !== $k ? 0 : ($counter + 1); |
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if ($counter === $k) { |
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return $k * $k; |
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} |
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} |
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return 0; |
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}; |
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for ($i = 0; $i < $m; $i++) { |
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$tmp = array_fill(0, $n, 0); |
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for ($j = $i; $j < $n; $j++) { |
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for ($k = 0; $k < $n; $k++) { |
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if (isset($matrix[$j][$k]) && $matrix[$j][$k] === 1) { |
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$tmp[$k]++; |
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} |
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} |
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$ans = max($ans, $helper($tmp, $j - $i + 1)); |
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} |
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} |
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return $ans; |
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} |
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public static function maximalSquare2(array $matrix): int |
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{ |
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[$m, $n, $ans] = [count($matrix), count($matrix[0]), 0]; |
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if ($m <= 0 || $n <= 0) { |
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return 0; |
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} |
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$dp = array_fill(0, $m + 1, array_fill(0, $n + 1, 0)); |
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for ($i = 1; $i <= $m; $i++) { |
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for ($j = 1; $j <= $n; $j++) { |
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if ($matrix[$i - 1][$j - 1] === 1) { |
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$dp[$i][$j] = min($dp[$i - 1][$j - 1], min($dp[$i - 1][$j], $dp[$i][$j - 1])) + 1; |
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$ans = max($ans, $dp[$i][$j]); |
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} |
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} |
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} |
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return $ans * $ans; |
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} |
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public static function maximalSquare3(array $matrix): int |
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{ |
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[$m, $n, $ans, $prev] = [count($matrix), count($matrix[0]), 0, 0]; |
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if ($m <= 0 || $n <= 0) { |
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return 0; |
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} |
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$dp = array_fill(0, $m + 1, 0); |
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for ($j = 0; $j < $n; $j++) { |
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for ($i = 1; $i <= $m; $i++) { |
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$temp = $dp[$i]; |
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if ($matrix[$i - 1][$j] === 1) { |
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$dp[$i] = min($dp[$i], min($dp[$i - 1], $prev)) + 1; |
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$ans = max($ans, $dp[$i]); |
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} else { |
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$dp[$i] = 0; |
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} |
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$prev = $temp; |
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} |
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} |
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return $ans * $ans; |
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} |
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} |
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imajinyun /
leetcode-php
