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Commit 2451db9

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Add iterative version of Euclidean algorithm.
1 parent c00c689 commit 2451db9

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4 files changed

+51
-15
lines changed

4 files changed

+51
-15
lines changed

‎src/algorithms/math/euclidean-algorithm/__test__/euclieanAlgorithm.test.js‎ renamed to ‎src/algorithms/math/euclidean-algorithm/__test__/euclideanAlgorithm.test.js‎

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import euclideanAlgorithm from '../euclideanAlgorithm';
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describe('euclideanAlgorithm', () => {
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it('should calculate GCD', () => {
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it('should calculate GCD recursively', () => {
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expect(euclideanAlgorithm(0, 0)).toBe(0);
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expect(euclideanAlgorithm(2, 0)).toBe(2);
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expect(euclideanAlgorithm(0, 2)).toBe(2);
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import euclideanAlgorithmIterative from '../euclideanAlgorithmIterative';
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describe('euclideanAlgorithmIterative', () => {
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it('should calculate GCD iteratively', () => {
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expect(euclideanAlgorithmIterative(0, 0)).toBe(0);
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expect(euclideanAlgorithmIterative(2, 0)).toBe(2);
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expect(euclideanAlgorithmIterative(0, 2)).toBe(2);
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expect(euclideanAlgorithmIterative(1, 2)).toBe(1);
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expect(euclideanAlgorithmIterative(2, 1)).toBe(1);
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expect(euclideanAlgorithmIterative(6, 6)).toBe(6);
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expect(euclideanAlgorithmIterative(2, 4)).toBe(2);
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expect(euclideanAlgorithmIterative(4, 2)).toBe(2);
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expect(euclideanAlgorithmIterative(12, 4)).toBe(4);
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expect(euclideanAlgorithmIterative(4, 12)).toBe(4);
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expect(euclideanAlgorithmIterative(5, 13)).toBe(1);
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expect(euclideanAlgorithmIterative(27, 13)).toBe(1);
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expect(euclideanAlgorithmIterative(24, 60)).toBe(12);
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expect(euclideanAlgorithmIterative(60, 24)).toBe(12);
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expect(euclideanAlgorithmIterative(252, 105)).toBe(21);
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expect(euclideanAlgorithmIterative(105, 252)).toBe(21);
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expect(euclideanAlgorithmIterative(1071, 462)).toBe(21);
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expect(euclideanAlgorithmIterative(462, 1071)).toBe(21);
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expect(euclideanAlgorithmIterative(462, -1071)).toBe(21);
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expect(euclideanAlgorithmIterative(-462, -1071)).toBe(21);
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});
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});
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/**
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* Recursive version of Euclidean Algorithm of finding greatest common divisor (GCD).
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* @param {number} originalA
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* @param {number} originalB
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* @return {number}
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*/
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/*Method 1: A bit Complex to understand*/
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export default function euclideanAlgorithm(originalA, originalB) {
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// Make input numbers positive.
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const a = Math.abs(originalA);
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const b = Math.abs(originalB);
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// To make algorithm work faster instead of subtracting one number from the other
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// we may use modulo operation.
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return (b === 0) ? a : euclideanAlgorithm(b, a % b);
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}
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/*Method 2: Easy to evaluate*/
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export default function euclideanAlgorithm2(originalA, originalB) {
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const a = Math.abs(originalA);
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const b = Math.abs(originalB);
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while(a != b){
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[a,b] = a>b : [a-b, b] : [a, b-a]
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}
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return a || b;
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}
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/**
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* Iterative version of Euclidean Algorithm of finding greatest common divisor (GCD).
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* @param {number} originalA
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* @param {number} originalB
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* @return {number}
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*/
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export default function euclideanAlgorithmIterative(originalA, originalB) {
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// Make input numbers positive.
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let a = Math.abs(originalA);
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let b = Math.abs(originalB);
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// Subtract one number from another until both numbers would become the same.
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// This will be out GCD. Also quit the loop if one of the numbers is zero.
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while (a && b && a !== b) {
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[a, b] = a > b ? [a - b, b] : [a, b - a];
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}
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// Return the number that is not equal to zero since the last subtraction (it will be a GCD).
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return a || b;
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}

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