Excel列名変換問題 via http://d.hatena.ne.jp/JunichiIto/20111102/1320253815

example.php

<?php
namespace Holy\Example;
require_once realpath(__DIR__ . '/lime.php');

$conv = function($string) {
    $i = 0;
    return array_sum(array_map(function($char) use (&$i) {
        $num = strpos('ABCDEFGHIJKLMNOPQRSTUVWXYZ', $char) + 1;
        $num *= pow(26, $i);
        $i++;
        return $num;
    }, str_split(strrev($string))));
};

// Test case
$t = new \lime_test();
// 問題1
$t->is(    1, $conv('A'));
$t->is(    2, $conv('B'));
$t->is(    3, $conv('C'));
$t->is(   25, $conv('Y'));
$t->is(   26, $conv('Z'));
$t->is(   27, $conv('AA'));
$t->is(   28, $conv('AB'));
$t->is(   51, $conv('AY'));
$t->is(   52, $conv('AZ'));
$t->is(   53, $conv('BA'));
$t->is(   54, $conv('BB'));
$t->is(  256, $conv('IV'));
$t->is(16384, $conv('XFD'));

example2.php

<?php
namespace Holy\Example;
require_once realpath(__DIR__ . '/lime.php');

class Converter
{

    const TO_NUMBER = 0;
    const TO_ALPHA  = 1;

    public static $map = array();

    public function __construct()
    {
        $alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        self::$map = array_combine(range(1, strlen($alphabet)), str_split($alphabet));
    }

    public function convert($mode, $value)
    {
        return ($mode == self::TO_NUMBER) ? $this->toNumber($value) : $this->toAlpha($value);
    }

    public function toNumber($string)
    {
        $num = 0;
        $length = count(self::$map);
        foreach (str_split(strrev($string)) as $i => $char) {
            $num += intval(array_search($char, self::$map)) * pow($length, $i);
        }
        return $num;
    }

    public function toAlpha($num)
    {
        $string = '';
        $length = count(self::$map);
        while ($num >= 1) {
            $key = $num % $length;
            $num = $num / $length;
            if ($key === 0) {
                $key = $length;
                $num--;
            }
            $string .= self::$map[$key];
        }
        return strrev($string);
    }
}

// Test case
$conv = new Converter();
$t = new \lime_test();
// 問題1
$t->is(    1, $conv->toNumber('A'));
$t->is(    2, $conv->toNumber('B'));
$t->is(    3, $conv->toNumber('C'));
$t->is(   25, $conv->toNumber('Y'));
$t->is(   26, $conv->toNumber('Z'));
$t->is(   27, $conv->toNumber('AA'));
$t->is(   28, $conv->toNumber('AB'));
$t->is(   51, $conv->toNumber('AY'));
$t->is(   52, $conv->toNumber('AZ'));
$t->is(   53, $conv->toNumber('BA'));
$t->is(   54, $conv->toNumber('BB'));
$t->is(  256, $conv->toNumber('IV'));
$t->is(16384, $conv->toNumber('XFD'));

// 問題2
$t->is(    1, $conv->convert(0, 'A'));
$t->is(    2, $conv->convert(0, 'B'));
$t->is(    3, $conv->convert(0, 'C'));
$t->is(   25, $conv->convert(0, 'Y'));
$t->is(   26, $conv->convert(0, 'Z'));
$t->is(   27, $conv->convert(0, 'AA'));
$t->is(   28, $conv->convert(0, 'AB'));
$t->is(   51, $conv->convert(0, 'AY'));
$t->is(   52, $conv->convert(0, 'AZ'));
$t->is(   53, $conv->convert(0, 'BA'));
$t->is(   54, $conv->convert(0, 'BB'));
$t->is(  256, $conv->convert(0, 'IV'));
$t->is(16384, $conv->convert(0, 'XFD'));

$t->is('A'  , $conv->convert(1,     1));
$t->is('B'  , $conv->convert(1,     2));
$t->is('C'  , $conv->convert(1,     3));
$t->is('Y'  , $conv->convert(1,    25));
$t->is('Z'  , $conv->convert(1,    26));
$t->is('AA' , $conv->convert(1,    27));
$t->is('AB' , $conv->convert(1,    28));
$t->is('AY' , $conv->convert(1,    51));
$t->is('AZ' , $conv->convert(1,    52));
$t->is('BA' , $conv->convert(1,    53));
$t->is('BB' , $conv->convert(1,    54));
$t->is('IV' , $conv->convert(1,   256));
$t->is('XFD', $conv->convert(1, 16384));

lime_testいれた＾o＾

問題2もやってみたけど仕様が「ただし、問題1で作ったプログラムを拡張すること。」だったので1から書き直した(ﾉ∀`)