php计算优惠信息求计算算法多谢

$arr=array('item_info_list' => Array
                                (
                                    '0' => Array
                                        (
                                            'sku_id' => '1003244250',
                                            'ware_id' => '1001418658',
                                            'jd_price' => '269.00',
                                            'sku_name' => '百事PEPSI 男式板鞋 2012新款夏季透气舒适男款经典休闲板鞋 猎人绿 40',
                                            'outer_sku_id' => '40872121106',
                                            'product_no' => '872121101 872121102 872121104 872121105',
                                            'gift_point' => '0',
                                            'item_total' => '1',
                                        )
                                    ,
                                    '1' => Array
                                        (
                                            'sku_id' => '1003244255',
                                            'ware_id' => '1001418658',
                                            'jd_price' => '269.00',
                                            'sku_name' => '百事PEPSI 男式板鞋 2012新款夏季透气舒适男款经典休闲板鞋 暗红 39',
                                            'outer_sku_id' => '39872121105',
                                            'product_no' => '872121101 872121102 872121104 872121105',
                                            'gift_point' => '0',
                                            'item_total' => '1',
                                        )

                                )
                            ,
                            'coupon_detail_list' => Array
                                (
                                    '0' => Array
                                        (
                                            'order_id' => '213978711',
                                            'sku_id' => '1003244250',
                                            'coupon_type' => '30-单品促销优惠',
                                            'coupon_price' => '170.00',
                                        )
                                    ,
                                    '1' => Array
                                        (
                                            'order_id' => '213978711',
                                            'sku_id' => '1003244255',
                                            'coupon_type' => '30-单品促销优惠',
                                            'coupon_price' => '170.00',
                                        )

                                )
)

foreach ($arr['item_info_list'] as $key=>$val)
{
    if(isset($arr['coupon_detail_list'][$key]))
        $arr['item_info_list'][$key] = array_merge($val, $arr['coupon_detail_list'][$key]);
}

print_r($arr);