<?php
$memoize = function ($fn, $cacheKeyFn = null, $limit = null) {
$cache = array();
return function () use ($fn, $cacheKeyFn, $limit, & $cache) {
$args = func_get_args();
if ($cacheKeyFn) {
$key = call_user_func_array($cacheKeyFn, $args);
} else {
$key = reset($args);
}
if (isset($cache[$key])) {
return $cache[$key];
}
$result = call_user_func_array($fn, $args);
if ($limit !== null && count($cache) === $limit) {
array_shift($cache);
}
$cache[$key] = $result;
return $result;
};
};
$numCalls = 0;
$memoFib = $memoize(
function ($n) use (& $memoFib, & $numCalls) {
$numCalls++;
if ($n === 1 || $n === 2) return 1;
return $memoFib($n - 1) + $memoFib($n - 2);
}
);
echo $numCalls . PHP_EOL;
echo $memoFib(1) . PHP_EOL;
echo $numCalls . PHP_EOL;
echo $memoFib(2) . PHP_EOL;
echo $numCalls . PHP_EOL;
- Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
- 0
1
1
1
2
- Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17
- Parse error: syntax error, unexpected T_FUNCTION in /in/PFYhF on line 3
Process exited with code 255. - Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5
- Parse error: parse error, unexpected T_FUNCTION in /in/PFYhF on line 3
Process exited with code 255. - Output for 4.3.2 - 4.3.4
- Parse error: parse error in /in/PFYhF on line 3
Process exited with code 255.
preferences:
236.62 ms | 401 KiB | 357 Q