/* Simple function */

const add = (n) => (n + 10);

const memoize = (fn) => {
	let cache = {};
  return (...args) => {
  	let n = args[0];
    if (n in cache) {
    	console.log('Getting result from cache.')
      return cache[n];
    } else {
    	console.log('Calculating result');
    	let result = fn(n);
      cache[n] = result;
      return result;
    }
  }
}

const memoizedAdd = memoize(add);
console.log(memoizedAdd(5));
console.log(memoizedAdd(6));
console.log(memoizedAdd(5));

/* recursive */
const factorial = memoize(
	(x) => {
		if (x === 0) return 1;
  	else return x * factorial(x - 1)
	}
)

console.log(factorial(5));
console.log(factorial(6));