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1 | 1 | (function (exports) { |
2 | | - 'use strict'; |
3 | | - |
4 | | - /** |
5 | | - * Advanced (optimised) method for checking if provided number is prime. |
6 | | - * For example for number 104743 it should return true, for 104744 - false. |
7 | | - * |
8 | | - * @module primes/is-prime |
9 | | - * @param {Number} number - Number that we check on prime. |
10 | | - * @returns {Boolean} Will return true if provided number is prime. |
11 | | - * |
12 | | - * @example |
13 | | - * var isPrime = require('path-to-algorithms/src/is-prime').isPrime; |
14 | | - * |
15 | | - * console.log(isPrime(7)); // true |
16 | | - * console.log(isPrime(18)); // false |
17 | | - */ |
18 | | - exports.isPrime = function (number) { |
19 | | - |
20 | | - if (number < 2) |
21 | | - return false; |
22 | | - |
23 | | - if (number % 2 === 0) |
24 | | - return (number === 2); |
25 | | - if (number % 3 === 0) |
26 | | - return (number === 3); |
27 | | - |
28 | | - var horizon = Math.floor(Math.sqrt(number)); |
29 | | - var factor = 5; |
30 | | - |
31 | | - while (factor <= horizon) { |
32 | | - |
33 | | - if (number % factor === 0) |
34 | | - return false; |
35 | | - |
36 | | - if (number % (factor + 2) === 0) |
37 | | - return false; |
38 | | - |
39 | | - factor += 6; |
40 | | - } |
41 | | - return true; |
42 | | - }; |
| 2 | + 'use strict'; |
| 3 | + |
| 4 | + /** |
| 5 | + * Advanced (optimised) method for checking if provided number is prime. |
| 6 | + * For example for number 104743 it should return true, for 104744 - false. |
| 7 | + * |
| 8 | + * @module primes/is-prime |
| 9 | + * @param {Number} number - Number that we check on prime. |
| 10 | + * @returns {Boolean} Will return true if provided number is prime. |
| 11 | + * |
| 12 | + * @example |
| 13 | + * var isPrime = require('path-to-algorithms/src/is-prime').isPrime; |
| 14 | + * |
| 15 | + * console.log(isPrime(7)); // true |
| 16 | + * console.log(isPrime(18)); // false |
| 17 | + */ |
| 18 | + exports.isPrime = function (number) { |
| 19 | + |
| 20 | + if (number < 2) { |
| 21 | + return false; |
| 22 | + } |
| 23 | + |
| 24 | + if (number % 2 === 0) { |
| 25 | + return (number === 2); |
| 26 | + } |
| 27 | + |
| 28 | + if (number % 3 === 0) { |
| 29 | + return (number === 3); |
| 30 | + } |
| 31 | + |
| 32 | + var horizon = Math.floor(Math.sqrt(number)); |
| 33 | + var factor = 5; |
| 34 | + |
| 35 | + while (factor <= horizon) { |
| 36 | + |
| 37 | + if (number % factor === 0) { |
| 38 | + return false; |
| 39 | + } |
| 40 | + |
| 41 | + if (number % (factor + 2) === 0) { |
| 42 | + return false; |
| 43 | + } |
| 44 | + factor += 6; |
| 45 | + } |
| 46 | + return true; |
| 47 | + }; |
43 | 48 |
|
44 | 49 | }(typeof exports === 'undefined' ? window : exports)); |
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