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Commit2451db9

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Add iterative version of Euclidean algorithm.
1 parentc00c689 commit2451db9

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4 files changed

+51
-15
lines changed

4 files changed

+51
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‎src/algorithms/math/euclidean-algorithm/__test__/euclieanAlgorithm.test.jsrenamed to‎src/algorithms/math/euclidean-algorithm/__test__/euclideanAlgorithm.test.js

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importeuclideanAlgorithmfrom'../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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importeuclideanAlgorithmIterativefrom'../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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exportdefaultfunctioneuclideanAlgorithm(originalA,originalB){
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// Make input numbers positive.
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consta=Math.abs(originalA);
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constb=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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exportdefaultfunctioneuclideanAlgorithm2(originalA,originalB){
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consta=Math.abs(originalA);
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constb=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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returna||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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exportdefaultfunctioneuclideanAlgorithmIterative(originalA,originalB){
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// Make input numbers positive.
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leta=Math.abs(originalA);
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letb=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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returna||b;
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}

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