数组小操作

1. 筛选数组中满足条件的key value

function maxZengSongTwo(array $arr,int $amount){
    ksort($arr);
    $level = '';
    $i = 1;
    foreach ($arr as $key=>$value){
        if($key==$amount){
            return ['key'=>$key,'value'=>$value];
        }
        if($key<$amount){
            $level = $key;
        }
        if($key>$amount &&$level<$amount){
            return ['key'=>$level,'value'=>$arr[$level]];
        }
        if($key<$amount && $level<$amount && $i==count($arr)){
            return ['key'=>$key,'value'=>$value];
        }
        $i ++;
    }
    return ['key'=>0,'value'=>0];
}