pub const fn factorial(n: u64) -> Result<u128, CombinatoricsError>Expand description
Returns n! using checked u128 arithmetic.
Overflow begins at n = 35.
§Errors
Returns CombinatoricsError::FactorialOverflow when the result no longer
fits in u128.
§Examples
use use_combinatorics::factorial;
assert_eq!(factorial(5)?, 120);