2623. Memoize

 

Boost Your JavaScript Performance with Memoization

Memoization is a technique used to speed up function execution by storing the results of expensive function calls and returning the cached result when the same inputs occur again.

What is Memoization?

Memoization involves caching the result of a function call based on its inputs. When the function is called again with the same inputs, it fetches the result from the cache instead of recomputing it, thus improving performance.

Why Do We Need Memoization?

Memoization is useful when:

  • A function is called multiple times with the same arguments.
  • The function involves heavy or repetitive computations.
  • We want to optimize time complexity, especially in recursive problems like Fibonacci sequences or dynamic programming solutions.

Approach

Here’s a simple JavaScript memoize function:

javascript
function memoize(fn) {
    let cached = {};
    return function(...args) {
        let n = JSON.stringify(args);
        if (n in cached) {
            return cached[n];
        } else {
            cached[n] = fn.apply(this, args);
            return cached[n];
        }
    }
}

This implementation uses JSON.stringify to convert the function’s arguments into a key for the cache. If the key exists, the cached result is returned; otherwise, the function is executed and the result is stored for future use.

Time and Space Complexity

  • Time Complexity: With memoization, the time complexity of recursive functions like Fibonacci can reduce from exponential O(2^n) to linear O(n) because each value is computed only once.

  • Space Complexity: The space complexity depends on the number of unique function calls and how much data you cache. For n unique calls, it will be O(n) in the worst case.

Memoization can greatly improve performance, especially for functions with repetitive computations!

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