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<?php
declare(strict_types=1);
namespace leetcode;
class ArrayTransformation
{
public static function transformArray(array $arr): array
if (empty($arr)) {
return [];
}
[$changed, $n] = [true, count($arr)];
$tmp = $arr;
while ($changed) {
$changed = false;
for ($i = 1; $i < $n - 1; $i++) {
if ($arr[$i - 1] < $arr[$i] && $arr[$i] > $arr[$i + 1]) {
$tmp[$i] -= 1;
$changed = true;
} elseif ($arr[$i - 1] > $arr[$i] && $arr[$i] < $arr[$i + 1]) {
$tmp[$i] += 1;
$arr = $tmp;
return $arr;
public static function transformArray2(array $arr): array
[$prev, $changed] = [$arr[0], false];
$curr = $arr[$i];
if ($prev < $curr && $curr > $arr[$i + 1]) {
[$changed, $arr[$i]] = [true, $curr - 1];
} elseif ($prev > $curr && $curr < $arr[$i + 1]) {
[$changed, $arr[$i]] = [true, $curr + 1];
$prev = $curr;