[PHP]相同Key值加總

$new_array = array();
foreach($old_array AS $k => $v){
    if( array_key_exists($k, $new_array) ){
        $new_array[$k] = $new_array[$k] + $v;
    }else{
        $new_array[$k] = $v; 
    }
}
ksort($new_array); // 依照Key值排序