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0529e19426
* [CREATE] Problem 28 solution for Project Euler * [UPDATE] Added an explanation for the formula used in the algorithm * [CREATE] Added Problem 35 for Project-Euler * [UPDATE] Little typo in the error string * [UPDATE] Some algorithm changes * [UPDATE] Fix test string * [UPDATE] Change prime numbers generator to import a standard sieve algorithm. * [UPDATE] Change sieve algorithm implementation and now the solution works well. Also added some optimizations
35 lines
1.2 KiB
JavaScript
35 lines
1.2 KiB
JavaScript
/**
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* Problem 35 - Circular primes
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*
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* @see {@link https://projecteuler.net/problem=35}
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*
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* The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.
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* There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97.
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* How many circular primes are there below one million?
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*
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* @author ddaniel27
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*/
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import { sieveOfEratosthenes } from '../Maths/SieveOfEratosthenesIntArray'
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function problem35 (n) {
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if (n < 2) {
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throw new Error('Invalid input')
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}
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const list = sieveOfEratosthenes(n).filter(prime => !prime.toString().match(/[024568]/)) // Get a list of primes without 0, 2, 4, 5, 6, 8
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const result = list.filter((number, _idx, arr) => {
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const str = String(number)
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for (let i = 0; i < str.length; i++) { // Get all rotations of the number
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const rotation = str.slice(i) + str.slice(0, i)
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if (!arr.includes(Number(rotation))) { // Check if the rotation is prime
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return false
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}
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}
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return true // If all rotations are prime, then the number is circular prime
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})
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return result.length + 1 // Add 2 to the result because 2 is a circular prime
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}
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export { problem35 }
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