【PHP】ポケモンタイプ相性表

参考
https://www.pokemon.co.jp/ex/sun_moon/fight/161215_01.html

ポケモンの防御側から見たタイプ相性表です

例：ギャラドス 水・飛行タイプ

["×4"]=>電気
["×0.5"]=>炎・水・格闘・鋼
["×0"]=>地面

コード

<?php

function getTypeDefenseTable(...$typeIds) {
    // 引数が空またはnullの場合はnullを返す
    if (empty($typeIds) || (count($typeIds) === 1 && (is_null($typeIds[0]) || $typeIds[0] === ''))) {
        return null;
    }
    
    // 引数が1つで文字列（カンマ区切り）の場合は配列に変換
    if (count($typeIds) === 1 && is_string($typeIds[0]) && strpos($typeIds[0], ',') !== false) {
        $typeIds = array_map('intval', explode(',', $typeIds[0]));
    }
    
    // 有効なタイプID（1〜18）のみを抽出
    $validTypeIds = array_filter((array)$typeIds, function($id) {
        return is_numeric($id) && $id >= 1 && $id <= 18;
    });
    
    if (empty($validTypeIds)) {
        return null;
    }
    
    $typeIds = array_map('intval', $validTypeIds);
    
    /**
     * 防御側から見た耐性チャート（最新世代準拠）
     * 各IDが飛んできた時、そのタイプ（INDEX）が受ける倍率の定義
     */
    $defenseChart = [
        1  => ['x2' => [7],          'x0.5' => [],           'x0' => [14]], // ノーマル
        2  => ['x2' => [3,9,13],     'x0.5' => [2,5,6,12,17,18], 'x0' => []], // ほのお
        3  => ['x2' => [4,5],        'x0.5' => [2,3,6,17],   'x0' => []], // みず
        4  => ['x2' => [9],          'x0.5' => [4,10,17],    'x0' => []], // でんき
        5  => ['x2' => [2,6,8,10,12], 'x0.5' => [3,4,5,9],    'x0' => []], // くさ
        6  => ['x2' => [2,7,9,13,17], 'x0.5' => [6],           'x0' => []], // こおり
        7  => ['x2' => [10,11,18],   'x0.5' => [12,13,16],   'x0' => []], // かくとう
        8  => ['x2' => [9,11],       'x0.5' => [5,7,8,12,18], 'x0' => []], // どく
        9  => ['x2' => [3,5,6],      'x0.5' => [8,13],       'x0' => [4]], // じめん
        10 => ['x2' => [4,6,13],     'x0.5' => [5,7,12],      'x0' => [9]], // ひこう
        11 => ['x2' => [12,14,16],   'x0.5' => [7,11],       'x0' => []], // エスパー
        12 => ['x2' => [2,10,13],    'x0.5' => [5,7,9],       'x0' => []], // むし
        13 => ['x2' => [3,5,7,9,17], 'x0.5' => [1,2,8,10],    'x0' => []], // いわ
        14 => ['x2' => [14,16],      'x0.5' => [8,12],       'x0' => [1,7]], // ゴースト
        15 => ['x2' => [6,15,18],    'x0.5' => [2,3,4,5],    'x0' => []], // ドラゴン
        16 => ['x2' => [7,12,18],    'x0.5' => [14,16],      'x0' => [11]], // あく
        17 => ['x2' => [2,7,9],      'x0.5' => [1,5,6,10,11,12,13,15,17,18], 'x0' => [8]], // はがね
        18 => ['x2' => [8,17],       'x0.5' => [7,12,16],    'x0' => [15]] // フェアリー
    ];

    $typeNames = [
        1 => 'ノーマル', 2 => 'ほのお', 3 => 'みず', 4 => 'でんき', 5 => 'くさ',
        6 => 'こおり', 7 => 'かくとう', 8 => 'どく', 9 => 'じめん', 10 => 'ひこう',
        11 => 'エスパー', 12 => 'むし', 13 => 'いわ', 14 => 'ゴースト', 15 => 'ドラゴン',
        16 => 'あく', 17 => 'はがね', 18 => 'フェアリー'
    ];

    // 攻撃タイプ(atk)ごとに最終倍率を計算
    $finalMultipliers = [];
    for ($atk = 1; $atk <= 18; $atk++) {
        $mult = 1.0;
        foreach ($typeIds as $defType) {
            if (!isset($defenseChart[$defType])) continue;
            
            $effect = $defenseChart[$defType];
            
            if (in_array($atk, $effect['x0'])) {
                $mult = 0;
                break; // 1つでも無効タイプがあれば最終倍率は0確定
            }
            if (in_array($atk, $effect['x2'])) $mult *= 2;
            if (in_array($atk, $effect['x0.5'])) $mult *= 0.5;
        }
        $finalMultipliers[$atk] = $mult;
    }

    // 倍率ごとに分類
    $groups = [
        '×4' => [],
        '×2' => [],
        '×0.5' => [],
        '×0.25' => [],
        '×0' => []
    ];

    foreach ($finalMultipliers as $atk => $mult) {
        if ($mult == 4.0) $groups['×4'][] = $typeNames[$atk];
        elseif ($mult == 2.0) $groups['×2'][] = $typeNames[$atk];
        elseif ($mult == 0.5) $groups['×0.5'][] = $typeNames[$atk];
        elseif ($mult == 0.25) $groups['×0.25'][] = $typeNames[$atk];
        elseif ($mult == 0.0) $groups['×0'][] = $typeNames[$atk];
    }

    return array_filter($groups); // 中身がある倍率のみ返す
}

// 例：くさ(5)・どく(8) の相性を表示
echo('<pre>');var_dump(getTypeDefenseTable(5,8));echo('</pre>');

結果

array(5) {
  ["×4"]=>
  array(1) {
    [0]=>
    string(9) "でんき"
  }
  ["×2"]=>
  array(0) {
  }
  ["×0.5"]=>
  array(4) {
    [0]=>
    string(9) "ほのお"
    [1]=>
    string(6) "みず"
    [2]=>
    string(12) "かくとう"
    [3]=>
    string(9) "はがね"
  }
  ["×0.25"]=>
  array(0) {
  }
  ["×0"]=>
  array(1) {
    [0]=>
    string(9) "じめん"
  }
}