2623. Memoize Write a class that allows getting and setting key-value pairs, however a time until expiration is associated with each key.

Given a function fn, return a memoized version of that function.

A memoized function is a function that will never be called twice with the same inputs. Instead it will return a cached value.

You can assume there are 3 possible input functions: sum, fib, and factorial.

sum accepts two integers a and b and returns a + b. Assume that if a value has already been cached for the arguments (b, a) where a != b, it cannot be used for the arguments (a, b). For example, if the arguments are (3, 2) and (2, 3), two separate calls should be made. fib accepts a single integer n and returns 1 if n <= 1 or fib(n - 1) + fib(n - 2) otherwise. factorial accepts a single integer n and returns 1 if n <= 1 or factorial(n - 1) * n otherwise.

Example 1:

Input: fnName = "sum" actions = ["call","call","getCallCount","call","getCallCount"] values = [[2,2],[2,2],[],[1,2],[]] Output: [4,4,1,3,2] Explanation: const sum = (a, b) => a + b; const memoizedSum = memoize(sum); memoizedSum(2, 2); // "call" - returns 4. sum() was called as (2, 2) was not seen before. memoizedSum(2, 2); // "call" - returns 4. However sum() was not called because the same inputs were seen before. // "getCallCount" - total call count: 1 memoizedSum(1, 2); // "call" - returns 3. sum() was called as (1, 2) was not seen before. // "getCallCount" - total call count: 2 Example 2:

Input: fnName = "factorial" actions = ["call","call","call","getCallCount","call","getCallCount"] values = [[2],[3],[2],[],[3],[]] Output: [2,6,2,2,6,2] Explanation: const factorial = (n) => (n <= 1) ? 1 : (n * factorial(n - 1)); const memoFactorial = memoize(factorial); memoFactorial(2); // "call" - returns 2. memoFactorial(3); // "call" - returns 6. memoFactorial(2); // "call" - returns 2. However factorial was not called because 2 was seen before. // "getCallCount" - total call count: 2 memoFactorial(3); // "call" - returns 6. However factorial was not called because 3 was seen before. // "getCallCount" - total call count: 2 Example 3:

Input: fnName = "fib" actions = ["call","getCallCount"] values = [[5],[]] Output: [8,1] Explanation: fib(5) = 8 // "call" // "getCallCount" - total call count: 1

Constraints:

0 <= a, b <= 105 1 <= n <= 10 0 <= actions.length <= 105 actions.length === values.length actions[i] is one of "call" and "getCallCount" fnName is one of "sum", "factorial" and "fib"

/**
 * @param {Function} fn
 * @return {Function}
 */
function memoize(fn) {
  const cache = new Map();
  return function (...args) {
    const key = args.toString();

    if (cache.has(key)) return cache.get(key);

    const result = fn(...args);
    cache.set(key, result);
    return result;
  };
}

/**
 * let callCount = 0;
 * const memoizedFn = memoize(function (a, b) {
 *	 callCount += 1;
 *   return a + b;
 * })
 * memoizedFn(2, 3) // 5
 * memoizedFn(2, 3) // 5
 * console.log(callCount) // 1
 */