n次元九九

nku.hs

nku :: Integer -> [Integer]
nku 0 = [1]
nku n = concat (map (\x -> map (*x) [1..9]) (nku (n - 1)))

nku.js

'use strict';

const nku = function (n) {
	const res = [];
	if (n === 0) {
		res.push(1);
	} else {
		nku(n - 1).forEach((x) => {
			[1, 2, 3, 4, 5, 6, 7 ,8, 9].forEach((e) => {
				res.push(e * x);
			})
		});
	}
	return res;
};