diff --git a/Maths/CollatzSequence.js b/Maths/CollatzSequence.js new file mode 100644 index 0000000000..d8ead61cc2 --- /dev/null +++ b/Maths/CollatzSequence.js @@ -0,0 +1,30 @@ +/** + * @function collatz + * @description Applies the Collatz Sequence on a specified number. + * The Collatz Sequence states that every natural number will always fall in a 1, 2, 4 loop when iterated under the following function: + * If the number is even, divide by 2, and if its odd, multiply it by 3 and add 1. + * + * @parama {Integer} n The number to apply the Collatz Sequence to. + * + * @return An array of steps and the final result.. + * + * @see [Collatz Conjecture](https://en.wikipedia.org/wiki/Collatz_conjecture) + * + * @example collatz(1) = { result: 1, steps: [] } + * @example collatz(5) = { result: 1, steps: [16, 8, 4, 2, 1] } +*/ +export function collatz (n) { + const steps = [] + + while (n !== 1) { + if (n % 2 === 0) { + n = n / 2 + } else { + n = 3 * n + 1 + } + + steps.push(n) + } + + return { result: n, steps: steps } +} diff --git a/Maths/test/CollatzSequence.test.js b/Maths/test/CollatzSequence.test.js new file mode 100644 index 0000000000..f837bd90d7 --- /dev/null +++ b/Maths/test/CollatzSequence.test.js @@ -0,0 +1,8 @@ +import { collatz } from '../CollatzSequence' + +describe('The Collatz Sequence', () => { + it('Should be 1', () => { + expect(collatz(1)).toStrictEqual({ result: 1, steps: [] }) + expect(collatz(5)).toStrictEqual({ result: 1, steps: [16, 8, 4, 2, 1] }) + }) +})