「第17回オフラインリアルタイムどう書くの参考問題」をPHPで解く

<?php

    class SCHEHERAZADE{

        /**
        * 回文基数
        * @param String 「17301」みたいな文字列
        * @return String 「5,38,100,218,236,5766,17300」みたいな文字列
        */
        public function get($input){
            $input = (int)$input;
            $ret = [];

            // 2からinput-1進数
            for($i=2;$i<$input;$i++){
                // 進数表現を取得
                $arr = $this->baseConvert($input, $i);
                // 逆順と等しければ回文
                if($arr === array_reverse($arr)){
                    $ret[] = $i;
                }
            }
            // 答えがなければ-
            return $ret ? implode(',', $ret) : '-';
        }

        /**
        * $base進数を求める
        * @param int 元の数
        * @param int 基数
        * @return array ex:数字が1001、基数が25のとき、[1, 15 ,1]
        */
        function baseConvert($num, $base){
            $result = [];
            while($num > 0){
                $result[] = $num % $base;
                $num = floor($num / $base);
            }
            return $result;
        }
    }

    // 以下はテスト
    $test = [
        ['17301', '5,38,100,218,236,5766,17300'],
        ['2', '-'],
        ['1', '-'],
        ['3', '2'],
        ['4', '3'],
        ['5', '2,4'],
        ['6', '5'],
        ['10', '3,4,9'],
        ['101', '10,100'],
        ['1001', '10,25,76,90,142,1000'],
        ['10001', '10,24,30,42,80,100,136,10000'],
        ['1212', '22,100,201,302,403,605,1211'],
        ['123412', '62,100,205,215,30852,61705,123411'],
        ['5179', '5178'],
        ['4919', '4918'],
        ['5791', '5790'],
        ['5498', '2748,5497'],
        ['453', '150,452'],
        ['134', '66,133'],
        ['8489', '27,652,8488'],
        ['1234', '22,616,1233'],
        ['5497', '41,238,5496'],
        ['4763', '19,35,432,4762'],
        ['3974', '17,27,1986,3973'],
        ['3521', '44,55,502,3520'],
        ['5513', '20,38,53,148,5512'],
        ['8042', '23,29,60,4020,8041'],
        ['7442', '37,60,121,3720,7441'],
        ['4857', '25,1618,4856'],
        ['22843', '49,69,91,141,430,22842'],
        ['194823', '84,121,21646,64940,194822'],
        ['435697', '160,169,235,626,1822,435696'],
        ['142', '3,7,70,141'],
        ['886', '5,14,442,885'],
        ['3102', '7,65,93,140,281,516,1033,1550,3101'],
        ['17326', '11,28,99,105,8662,17325'],
        ['32982', '13,72,238,477,716,1433,5496,10993,16490,32981'],
        ['36', '5,8,11,17,35'],
        ['37', '6,36'],
        ['251', '8,250'],
        ['252', '5,10,17,20,27,35,41,62,83,125,251'],
        ['253', '12,14,22,252'],
        ['6643', '2,3,9,81,90,510,948,6642'],
        ['5040', '71,79,83,89,104,111,119,125,139,143,167,179,209,239,251,279,314,335,359,419,503,559,629,719,839,1007,1259,1679,2519,5039'],
        ['9240', '23,38,62,104,109,119,131,139,153,164,167,209,219,230,263,279,307,329,384,419,439,461,615,659,769,839,923,1154,1319,1539,1847,2309,3079,4619,9239'],
    ];

    $scheherazade = new SCHEHERAZADE();
    foreach($test as $key=>$data){
        $answer = $scheherazade->get($data[0]);
        if($answer !== $data[1]){
            print('えらー');
        }
    }