/**

* Time Complexity: O(n)

* Space Complexity: O(1)

* @param {Number} n

* @return {Number}

*/

const factorialRecursive = (n) => {

if (n < 0) throw new Error('Factorial of negative numbers isn\'t defined');

else if (n == 0) return 1;

else if (n == 1) return 1;

return n * factorialRecursive(n-1);

};

/**

* Time Complexity: O(n)

* Space Complexity: O(1)

* @param {Number} n

* @return {Number}

*/

const factorialIterative = (n) => {

if (n < 0) throw new Error('Factorial of negative numbers isn\'t defined');

else if (n == 0) return 1;

let finalValue = n;

for (let i = 2; i< n; i += 1) {

finalValue *= i;

}

return finalValue;

};

module.exports = {factorialIterative, factorialRecursive};