Leetcode #Memoize

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




</p>
<p><strong>Example 2:</strong></p>

<p><strong>Input:</strong><br>
</p>

<pre class="brush:php;toolbar:false">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"

Solution

As you continue to develop and optimize your JavaScript applications, remember the power of memoization. By identifying the right functions to memoize and implementing the appropriate caching strategies, you can unlock significant performance gains and create a more seamless and responsive user experience for your customers.

I hope this article helps. If you like the article, please leave a like and feel free to leave any concerns on the comment section. That is all for today.

The above is the detailed content of Leetcode #Memoize. For more information, please follow other related articles on the PHP Chinese website!