Online PHP editor | output for f6FQv

<?php $array = [ ["key" => 0, "value" => 25], ["key" => 1, "value" => 25], ["key" => 2, "value" => 25], ["key" => 3, "value" => 33], ["key" => 4, "value" => 45], ["key" => 5, "value" => 66], ["key" => 6, "value" => 66], ["key" => 7, "value" => 66], ["key" => 8, "value" => 66], ["key" => 9, "value" => 55], ]; $r = []; $lastKey = ''; foreach($array as $k => $v){ if(in_array($v['value'], array_column($r, 'value'))){ $lastKey = $v['key']; }else{ if($lastKey && !in_array($lastKey, array_column($r, 'key'))){ end($r); $r[] = [ 'key' => $lastKey, 'value' => $r[key($r)]['value']]; } $r[] = [ 'key' => $v['key'] , 'value' => $v['value'] ]; $lastKey = $v['key']; } } echo '<pre>'; print_r($r);