{ "data": { "question": { "questionId": "2731", "questionFrontendId": "2623", "boundTopicId": null, "title": "Memoize", "titleSlug": "memoize", "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 returned a cached value.

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

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Example 1:

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\nInput\n"sum"\n["call","call","getCallCount","call","getCallCount"]\n[[2,2],[2,2],[],[1,2],[]]\nOutput\n[4,4,1,3,2]\n\nExplanation\nconst sum = (a, b) => a + b;\nconst memoizedSum = memoize(sum);\nmemoizedSum(2, 2); // Returns 4. sum() was called as (2, 2) was not seen before.\nmemoizedSum(2, 2); // Returns 4. However sum() was not called because the same inputs were seen before.\n// Total call count: 1\nmemoizedSum(1, 2); // Returns 3. sum() was called as (1, 2) was not seen before.\n// Total call count: 2\n
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Example 2:

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\nInput\n"factorial"\n["call","call","call","getCallCount","call","getCallCount"]\n[[2],[3],[2],[],[3],[]]\nOutput\n[2,6,2,2,6,2]\n\nExplanation\nconst factorial = (n) => (n <= 1) ? 1 : (n * factorial(n - 1));\nconst memoFactorial = memoize(factorial);\nmemoFactorial(2); // Returns 2.\nmemoFactorial(3); // Returns 6.\nmemoFactorial(2); // Returns 2. However factorial was not called because 2 was seen before.\n// Total call count: 2\nmemoFactorial(3); // Returns 6. However factorial was not called because 3 was seen before.\n// Total call count: 2\n
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Example 3:

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\nInput\n"fib"\n["call","getCallCount"]\n[[5],[]]\nOutput\n[8,1]\n\nExplanation\nfib(5) = 8\n// Total call count: 1\n\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.

\"], \"typescript\": [\"Typescript\", \"

TypeScript 4.5.4, Node.js 16.13.2.

\\r\\n\\r\\n

Your code is run with --harmony flag, enabling new ES2020 features.

\\r\\n\\r\\n

lodash.js library is included by default.

\"]}", "libraryUrl": null, "adminUrl": null, "challengeQuestion": null, "__typename": "QuestionNode" } } }