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<?php $array=[ [36868=>3], [2112=>3], [35901=>3], [6496=>3], [87=>3], [36868=>3], [68=>3], [9068=>3], [47=>3] ]; foreach($array as $subarray){ foreach($subarray as $k=>$v){ if(!isset($result[$k])){ $result[$k]=$subarray; }else{ $result[$k][$k]+=$v; } } } var_export(array_values($result));
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
array ( 0 => array ( 36868 => 6, ), 1 => array ( 2112 => 3, ), 2 => array ( 35901 => 3, ), 3 => array ( 6496 => 3, ), 4 => array ( 87 => 3, ), 5 => array ( 68 => 3, ), 6 => array ( 9068 => 3, ), 7 => array ( 47 => 3, ), )

preferences:
155.64 ms | 408 KiB | 5 Q