求一个分时段计费的算法啊，chatgpt都被问傻了也给不了正确的答案

$rates = [
    {
        "start" => "00:00",
        "end" => "12:00",
        "rate" => 3
    },
    {
        "start" => "12:00",//开始时间
        "end" => "24:00", //结束时间
        "rate" => 4 //分钟单价
    }
]

$rates = [
    {
        "start" => "12:00",
        "end" => "02:00",
        "rate" => 3
    },
    {
        "start" => "02:00",//开始时间
        "end" => "12:00", //结束时间
        "rate" => 4 //分钟单价
    }
]

public static function calculateCost($start, $end, $rates){
    //这里就是算法了
}