Merge pull request TheAlgorithms#732 from MrDoomy/feat/memoize-func

Feat: Added Memoize Func

Author: pomkarnath98

Cache/Memoize.js

@@ -0,0 +1,42 @@
+/**
+ * Memoize
+ *
+ * From [Wikipedia](https://en.wikipedia.org/wiki/Memoization),
+ * memoization is an optimization technique
+ * used primarily to speed up computer programs,
+ * by storing the results of expensive function calls
+ * and returning the cached result when the same inputs occur again
+ *
+ * This function is a first class objects,
+ * which lets us use it as [Higher-Order Function](https://eloquentjavascript.net/05_higher_order.html)
+ * and return another function
+ *
+ * @param {Function} func Original function
+ * @returns {Function} Memoized function
+ */
+export const memoize = (func) => {
+ // Initialization of a slot to store the function result
+ const cache = {}
+
+ return (...args) => {
+ // Retrieving the first argument of the function
+ const [arg] = args
+
+ /**
+ * Checks if the argument is already present in the cache,
+ * then return the associated value / result
+ */
+ if (arg in cache) {
+ return cache[arg]
+ }
+
+ /**
+ * If the argument is not yet present in the cache,
+ * execute original function and save its value / result in cache,
+ * finally return it
+ */
+ const result = func(arg)
+ cache[arg] = result
+ return result
+ }
+}

Cache/test/Memoize.test.js

@@ -0,0 +1,37 @@
+import { memoize } from '../Memoize'
+
+const fibonacci = (n) => {
+ if (n < 2) {
+ return n
+ }
+
+ return fibonacci(n - 2) + fibonacci(n - 1)
+}
+
+const factorial = (n) => {
+ if (n === 0) {
+ return 1
+ }
+
+ return n * factorial(n - 1)
+}
+
+describe('Memoize', () => {
+ it('expects the fibonacci function to use the cache on the second call', () => {
+ const memoFibonacci = memoize(fibonacci)
+
+ expect(memoFibonacci(5)).toEqual(fibonacci(5))
+ expect(memoFibonacci(5)).toEqual(5)
+ expect(memoFibonacci(10)).toEqual(fibonacci(10))
+ expect(memoFibonacci(10)).toEqual(55)
+ })
+
+ it('expects the factorial function to use the cache on the second call', () => {
+ const memoFactorial = memoize(factorial)
+
+ expect(memoFactorial(5)).toEqual(factorial(5))
+ expect(memoFactorial(5)).toEqual(120)
+ expect(memoFactorial(10)).toEqual(factorial(10))
+ expect(memoFactorial(10)).toEqual(3628800)
+ })
+})