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function factorial($n) | |
{ | |
if ($n == 1) { | |
return $n; | |
} | |
return $n * factorial($n-1); | |
} | |
function tail_factorial($n, $acc = 1) | |
{ | |
if ($n == 1) { | |
return $acc; | |
} | |
return tail_factorial($n-1, $n * $acc); | |
} | |
function unrolled_factorial($n) | |
{ | |
$acc = 1; | |
while ($n > 1) { | |
$acc *= $n--; | |
} | |
return $acc; | |
} | |
function goto_factorial($n) | |
{ | |
$acc = 1; | |
f: | |
if ($n == 1) { | |
return $acc; | |
} | |
$acc *= $n--; | |
goto f; | |
} | |
function trampo_factorial($n, $acc = 1) | |
{ | |
if ($n == 1) { | |
return $acc; | |
} | |
return function() use ($n, $acc) { return trampo_factorial($n-1, $n * $acc); }; | |
} | |
function trampoline(callable $c, ...$args) | |
{ | |
while (is_callable($c)) { $c = $c(...$args); } return $c; | |
} | |
echo trampoline('trampo_factorial', 42); |
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