Advent of code 2015/21

Ajax Direct

$items = [
    "weapons" => [
        [8,  4, 0], // Dagger
        [10, 5, 0], // Shortsword
        [25, 6, 0], // Warhammer
        [40, 7, 0], // Longsword
        [74, 8, 0], // Greataxe
    ],
    "armor" => [
        [0,   0, 0], // None
        [13,  0, 1], // Leather
        [31,  0, 2], // Chainmail
        [53,  0, 3], // Splintmail
        [75,  0, 4], // Bandedmail
        [102, 0, 5], // Platemail
    ],
    "rings" => [
        [0,   0, 0], // None 1
        [0,   0, 0], // None 2
        [25,  1, 0], // Damage +1
        [50,  2, 0], // Damage +2
        [100, 3, 0], // Damage +3
        [20,  0, 1], // Defense +1
        [40,  0, 2], // Defense +2
        [80,  0, 3], // Defense +3
    ],
];

$solution_1 = PHP_INT_MAX;
$solution_2 = 0;
$boss_stats = $input->numbers();

foreach ($items["weapons"] as $weapon) {
    foreach ($items["armor"] as $armor) {
        foreach ($items["rings"] as $ring1) {
            foreach ($items["rings"] as $ring2) {
                if ($ring1 === $ring2) continue;

                $cost = $weapon[0] + $armor[0] + $ring1[0] + $ring2[0];

                $player = [
                    "hp"     => 100,
                    "damage" => $weapon[1] + $armor[1] + $ring1[1] + $ring2[1],
                    "armor"  => $weapon[2] + $armor[2] + $ring1[2] + $ring2[2]
                ];

                $boss = [
                    "hp"     => $boss_stats[0],
                    "damage" => $boss_stats[1],
                    "armor"  => $boss_stats[2],
                ];

                while ($player["hp"] > 0 && $boss["hp"] > 0) {
                    $boss["hp"] -= max(1, $player["damage"] - $boss["armor"]);
                    $player["hp"] -= max(1, $boss["damage"] - $player["armor"]);
                }

                if ($boss["hp"] <= 0) {
                    $solution_1 = min($solution_1, $cost);
                } else {
                    $solution_2 = max($solution_2, $cost);
                }
            }
        }
    }
}