Memoize | #2634 | LeetCode Solution
Author: neptune | 12th-Sep-2023
Problem: Memoize | #2634 | LeetCode
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`.
`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
"sum"
["call","call","getCallCount","call","getCallCount"]
[[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); // Returns 4. sum() was called as (2, 2) was not seen before.
memoizedSum(2, 2); // Returns 4. However sum() was not called because the same inputs were seen before.
// Total call count: 1
memoizedSum(1, 2); // Returns 3. sum() was called as (1, 2) was not seen before.
// Total call count: 2
Example 2:
Input
"factorial"
["call","call","call","getCallCount","call","getCallCount"]
[[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); // Returns 2.
memoFactorial(3); // Returns 6.
memoFactorial(2); // Returns 2. However factorial was not called because 2 was seen before.
// Total call count: 2
memoFactorial(3); // Returns 6. However factorial was not called because 3 was seen before.
// Total call count: 2
Example 3:
Input
"fib"
["call","getCallCount"]
[[5],[]]
Output
[8,1]
Explanation
fib(5) = 8
// Total call count: 1
Solution:
/**
* @param {Function} fn
*/
function memoize(fn) {
// Create a Map to store cached results
const cache = new Map();
return function (...args) {
// Create a unique key based on the input arguments
const key = args.join(",");
if (cache.has(key)) {
// If the result is already cached, return it
return cache.get(key);
} else {
// If not cached, compute the result using the original function
const result = fn(...args);
// Cache the result for future use
cache.set(key, result);
return result;
}
};
}
Explanation:
To implement the `memoize` function as described, you can use a caching mechanism to store the results of previous function calls based on their input arguments. Here's the code with step-by-step explanations:
Let's break down the code step by step:
1. The `memoize` function is defined, taking a single parameter `fn`, which is the function to be memoized.
2. Inside the `memoize` function, a `cache` variable is created as a new `Map` object. This map will be used to store the results of function calls based on their input arguments.
3. The `memoize` function returns a new function created using a closure. This new function accepts any number of arguments using the rest operator `...args`.
4. Inside the returned function:
- It creates a unique key based on the input arguments by converting the arguments array into a JSON string using `JSON.stringify(args)`. This key uniquely represents the specific combination of input arguments.
5. It checks if the `cache` already contains a result associated with the computed key using `cache.has(key)`.
- If the result is already cached, it returns the cached result using `cache.get(key)`.
- If not cached, it computes the result by invoking the original function `fn` with the provided arguments using `fn(...args)`.
6. After computing the result, it caches the result in the `cache` map using `cache.set(key, result)` so that it can be reused if the same input arguments are encountered again in the future.
7. Finally, it returns the computed result, whether it was fetched from the cache or freshly computed.
In summary, the `memoize` function creates a memoized version of a given function `fn`. It stores the results of previous function calls in a cache based on their input arguments, ensuring that the same inputs do not trigger redundant function calls, and returning the cached result instead.
#JavaScript #Hackerrank #Python #Motivation #AI #React.js #Testing #Interview #SQL #Selenium #LeetCode #Problem Solving #Machine learning #Java #GPT #AWS #API #IT #Algorithms #Github #Jobs #Microservice #Certifications #Projects #Google #Django #Story #Pip #Data Science #Postman #Health #Twitter #Elon Musk #Node.js
To Be Or Not To Be | #2704 | LeetCode SolutionAuthor: neptune | 03rd-Sep-2023
#JavaScript #LeetCode
Write a function that helps developers test their code. It should take in any value and return an object with the following two functions...
Apply Transform Over Each Element in Array | #2635 | LeetCode SolutionAuthor: neptune | 05th-Sep-2023
#JavaScript #LeetCode
Given an integer array `arr` and a mapping function `fn`, return a new array with a transformation applied to each element...
Counter | #2620 | LeetCode SolutionAuthor: neptune | 02nd-Sep-2023
#JavaScript #LeetCode
Given an integer n, return a counter function. This counter function returns n and then n + 1, n + 2, etc...
Function Composition | #2629 | LeetCode SolutionAuthor: neptune | 09th-Sep-2023
#JavaScript #LeetCode
Given an array of functions [f1, f2, f3, ..., fn], return a new function fn that is the function composition of the array of functions...
Counter 2 | #2665 | LeetCode SolutionAuthor: neptune | 04th-Sep-2023
#JavaScript #LeetCode
Write function 'createCounter' It accept an initial integer 'init' It should return an object with three functions- increment() , decrement(), reset()...
Arrow Functions in JavaScript | ES6Author: neptune | 26th-Mar-2023
#JavaScript #React.js
In this article, we will explore the syntax and usage of arrow functions in detail, along with some examples...
Array Reduce Transformation | #2626 | LeetCode SolutionAuthor: neptune | 09th-Sep-2023
#JavaScript #LeetCode
Given an integer array `nums` and a reducer function `fn`, and an initial value `init`, return a reduced array...
Add Two Promises | #2723 | LeetCode SolutionAuthor: neptune | 12th-Sep-2023
#JavaScript #LeetCode
Given two promises `promise1` and `promise2`, return a new `promise`. `promise1` and `promise2` will both resolve with a number...
Different ways to handle state in React applicationsAuthor: neptune | 21st-Jun-2023
#JavaScript #React.js
This article explores different ways to manage states in React, including local component state, context API, and state management libraries like Redux...
Filter Elements from Array | #2634 | LeetCode SolutionAuthor: neptune | 06th-Sep-2023
#JavaScript #LeetCode
Given an integer array `arr` and a filtering function `fn`, return a filtered array `filteredArr`...
Is Object Empty | #2727 | LeetCode | JavaScript SolutionAuthor: neptune | 01st-Sep-2023
#JavaScript #LeetCode
Given an object or an array, return if it is empty...
Chunk Array | #2677 | LeetCode SolutionAuthor: neptune | 19th-Sep-2023
#JavaScript #LeetCode
Given an array arr and a chunk `size`, return a `chunked` array...
Managing Virtual Environments in React JavaScript ProjectsAuthor: neptune | 28th-Jun-2023
#JavaScript #React.js
Virtual environments are a valuable tool in React JavaScript projects as they allow developers to isolate dependencies, manage package versions, and maintain project consistency...
Allow One Function Call | #2666 | LeetCode SolutionAuthor: neptune | 11th-Sep-2023
#JavaScript #LeetCode
Given a function `fn`, return a new function that is identical to the original function except that it ensures `fn` is called at most once...
Array Prototype Last | #2619 | LeetCode SolutionAuthor: neptune | 20th-Sep-2023
#JavaScript #LeetCode
Write code that enhances all arrays such that you can call the `array.last()` method on any array and it will return the last element...
All You Need to Know About Pure Functions & Impure Functions in JavaScriptAuthor: neptune | 02nd-Apr-2023
#JavaScript #React.js
You should try to use pure functions whenever possible and avoid using impure functions unless necessary...
A Guide to Writing Clean, Readable, and Maintainable Code in JavaScriptAuthor: neptune | 23rd-Feb-2024
#JavaScript
By incorporating these principles into your coding practices, you contribute to creating code that is not only functional but also maintainable and easily understandable by your peers...
From REST to GraphQL: The Future of API DesignAuthor: neptune | 25th-Feb-2024
#JavaScript
Unlike traditional REST APIs, GraphQL provides a more flexible and intuitive approach to data querying and retrieval...
6 Brilliant JavaScript Frameworks for Every DeveloperAuthor: neptune | 16th-Feb-2024
#JavaScript
JavaScript's web development with frameworks like Synaptic.js for neural networks, OpenCV.js for multimedia processing, D3.js for dynamic data visualizations, Compromise.js for efficient NLP, ConvNet...
State in React: Component State and Controlling BehaviorAuthor: neptune | 21st-Feb-2024
#JavaScript #React.js
React, a popular JavaScript library for building user interfaces, introduces the concept of state and lifecycle methods to help developers manage the dynamic nature of components...
Decode Secret Language of React: Game-Changer for Web DevelopersAuthor: neptune | 25th-Feb-2024
#JavaScript #React.js
JSX is a syntax extension for JavaScript recommended by React for describing what the UI should look like...
View More