Rsa97

$result = implode(
  '',
  array_unique(
    array_merge(
      preg_split('//u', 'abce', -1, PREG_SPLIT_NO_EMPTY),
      preg_split('//u', 'cbegdy', -1, PREG_SPLIT_NO_EMPTY)
    )
  )
);

const isOverlap = (arr1, arr2) => arr1.some((el) => arr2.includes(el));
console.log(isOverlap([20, 50], [50, 100]));
// true

<?php
$array = [
    253 => 'я',
    189 => 'c',
    185 => 'в',
    298 => 'finish'
  ];
$arrgs = [];
$curr = &$arrgs;
foreach ($array as $idx => $val) {
    if (!array_key_exists($idx, $curr)) {
        $curr[$idx] = [];
    }
    $curr = &$curr[$idx];
}
$curr = $val;
print_r($arrgs);
//Array(
//  [253] => Array(
//    [189] => Array(
//      [185] => Array(
//        [298] => finish
//      )
//    )
//  )
//)

const count_dvr = (number_cam) => {
  if (number_cam < 1) {
    return 0;
  }
  if (number_cam < 5) {
    return 4;
  }
  if (number_cam < 9) {
    return 8;
  }
  if (number_cam < 17) {
    return 16;
  }
  if (number_cam < 33) {
    return 32;
  }
  return 64;
};
console.log(count_dvr(17));
// 32