mtdowling

<?php

$fibMemo = call_user_func(function () {
    $memo = array(0 => 0, 1 => 1);
    $fib = function ($n) use (&$memo, &$fib) {
        if (!isset($memo[$n])) {
            $memo[$n] = $fib($n - 1) + $fib($n - 2);
        }
        return $memo[$n];
    };