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Memoization in PHP

Honeybadger Staff on March 01, 2024

This article was originally written by Michael Barasa on the Honeybadger Developer Blog. Memoization is an important optimization technique in sof...

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Lito • Mar 1 '24 • Edited

You don't have to use an external variable for cache, you can use a static variable from the method:

function fibonacci(int $n): int
{
    static $cache = [];

    if (isset($cache[$n])) {
        return $cache[$n];
    }

    if (($n === 0) || ($n === 1)) {
        return $cache[$n] = $n;
    }

    return $cache[$n] = intval(fibonacci($n - 1) + fibonacci($n - 2));
}

for ($i = 0; $i < 80; $i++) {
    echo fibonacci($i).' ';
}