{ "data": { "question": { "questionId": "2744", "questionFrontendId": "2630", "boundTopicId": null, "title": "Memoize II", "titleSlug": "memoize-ii", "content": "

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

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

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fn can be any function and there are no constraints on what type of values it accepts. Inputs are considered identical if they are === to each other.

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Example 1:

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\nInput: \ngetInputs = () => [[2,2],[2,2],[1,2]]\nfn = function (a, b) { return a + b; }\nOutput: [{"val":4,"calls":1},{"val":4,"calls":1},{"val":3,"calls":2}]\nExplanation:\nconst inputs = getInputs();\nconst memoized = memoize(fn);\nfor (const arr of inputs) {\n  memoized(...arr);\n}\n\nFor the inputs of (2, 2): 2 + 2 = 4, and it required a call to fn().\nFor the inputs of (2, 2): 2 + 2 = 4, but those inputs were seen before so no call to fn() was required.\nFor the inputs of (1, 2): 1 + 2 = 3, and it required another call to fn() for a total of 2.\n
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Example 2:

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\nInput: \ngetInputs = () => [[{},{}],[{},{}],[{},{}]] \nfn = function (a, b) { return ({...a, ...b}); }\nOutput: [{"val":{},"calls":1},{"val":{},"calls":2},{"val":{},"calls":3}]\nExplanation:\nMerging two empty objects will always result in an empty object. It may seem like there should only be 1 call to fn() because of cache-hits, however none of those objects are === to each other.\n
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Example 3:

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\nInput: \ngetInputs = () => { const o = {}; return [[o,o],[o,o],[o,o]]; }\nfn = function (a, b) { return ({...a, ...b}); }\nOutput: [{"val":{},"calls":1},{"val":{},"calls":1},{"val":{},"calls":1}]\nExplanation:\nMerging two empty objects will always result in an empty object. The 2nd and 3rd third function calls result in a cache-hit. This is because every object passed in is identical.\n
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Constraints:

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Node.js 16.13.2.

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Your code is run with --harmony flag, enabling new ES6 features.

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lodash.js library is included by default.

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For Priority Queue / Queue data structures, you may use 5.3.0 version of datastructures-js/priority-queue and 4.2.1 version of datastructures-js/queue.

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TypeScript 5.1.6, Node.js 16.13.2.

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Your code is run with --harmony flag, enabling new ES2022 features.

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lodash.js library is included by default.

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