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Commit 845b820

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30 days javaScript 11th problme solved
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/*
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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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You can assume there are 3 possible input functions: sum, fib, and factorial.
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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.
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fib accepts a single integer n and returns 1 if n <= 1 or fib(n - 1) + fib(n - 2) otherwise.
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factorial accepts a single integer n and returns 1 if n <= 1 or factorial(n - 1) * n otherwise.
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Example 1:
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Input:
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fnName = "sum"
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actions = ["call","call","getCallCount","call","getCallCount"]
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values = [[2,2],[2,2],[],[1,2],[]]
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Output: [4,4,1,3,2]
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Explanation:
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const sum = (a, b) => a + b;
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const memoizedSum = memoize(sum);
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memoizedSum(2, 2); // "call" - returns 4. sum() was called as (2, 2) was not seen before.
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memoizedSum(2, 2); // "call" - returns 4. However sum() was not called because the same inputs were seen before.
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// "getCallCount" - total call count: 1
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memoizedSum(1, 2); // "call" - returns 3. sum() was called as (1, 2) was not seen before.
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// "getCallCount" - total call count: 2
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Example 2:
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Input:
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fnName = "factorial"
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actions = ["call","call","call","getCallCount","call","getCallCount"]
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values = [[2],[3],[2],[],[3],[]]
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Output: [2,6,2,2,6,2]
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Explanation:
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const factorial = (n) => (n <= 1) ? 1 : (n * factorial(n - 1));
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const memoFactorial = memoize(factorial);
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memoFactorial(2); // "call" - returns 2.
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memoFactorial(3); // "call" - returns 6.
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memoFactorial(2); // "call" - returns 2. However factorial was not called because 2 was seen before.
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// "getCallCount" - total call count: 2
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memoFactorial(3); // "call" - returns 6. However factorial was not called because 3 was seen before.
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// "getCallCount" - total call count: 2
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Example 3:
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Input:
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fnName = "fib"
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actions = ["call","getCallCount"]
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values = [[5],[]]
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Output: [8,1]
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Explanation:
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fib(5) = 8 // "call"
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// "getCallCount" - total call count: 1
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Constraints:
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0 <= a, b <= 105
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1 <= n <= 10
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1 <= actions.length <= 105
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actions.length === values.length
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actions[i] is one of "call" and "getCallCount"
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fnName is one of "sum", "factorial" and "fib"
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*/
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type Fn = (...params: number[]) => number;
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function memoize(fn: Fn): Fn {
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const cache: { [key: string]: number } = {};
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return function (...args: number[]): number {
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const key = args.join(',');
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if (key in cache) {
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return cache[key];
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}
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const result = fn(...args);
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cache[key] = result;
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return result;
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}
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}
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/**
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* let callCount = 0;
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* const memoizedFn = memoize(function (a, b) {
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* callCount += 1;
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* return a + b;
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* })
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* memoizedFn(2, 3) // 5
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* memoizedFn(2, 3) // 5
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* console.log(callCount) // 1
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*/

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