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Commite36c441

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Bruce-Feldmantrekhleb
authored andcommitted
Minor fixes. (trekhleb#91)
* Get Bit: Make more terse* Power of two: Allowed 1 as a valid power of 2.Power of two: Removed unnecessary exception throwing.* Fisher Yates: Made more terse* Least Common Multiple: Fill undefined value* Greatest Common Divisor: Fill undefined value.Greatest Common Divisor: Make more terse.
1 parent93bfe97 commite36c441

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10 files changed

+15
-75
lines changed

10 files changed

+15
-75
lines changed

‎src/algorithms/math/bits/README.md

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@@ -2,12 +2,7 @@
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####Get Bit
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5-
This method shifts`1` over by`bitPosition` bits, creating a
6-
value that looks like`00100`. Then we perform`AND` operation
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that clears all bits from the original number except the
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`bitPosition` one. Then we compare the result with zero. If
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result is zero that would mean that original number has`0` at
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position`bitPosition`.
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This method shifts the relevant bit to the zeroth position. Then we perform 'AND' operation with one which has bit pattern like '00001'. This clears all bits from the original number except the relevant one. If the relevant bit is one, the result is '1', otherwise the result is '0'.
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>See`getBit` function for further details.
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‎src/algorithms/math/bits/getBit.js

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@@ -4,5 +4,5 @@
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*@return {number}
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*/
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exportdefaultfunctiongetBit(number,bitPosition){
7-
return(number&(1<<bitPosition))===0 ?0 :1;
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return(number>>bitPosition)&1;
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}

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

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@@ -2,7 +2,7 @@ import euclideanAlgorithm from '../euclideanAlgorithm';
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describe('euclideanAlgorithm',()=>{
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it('should calculate GCD',()=>{
5-
expect(euclideanAlgorithm(0,0)).toBeNull();
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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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expect(euclideanAlgorithm(1,2)).toBe(1);
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@@ -1,32 +1,11 @@
11
/**
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*@param {number} originalA
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*@param {number} originalB
4-
*@return {number|null}
4+
*@return {number}
55
*/
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exportdefaultfunctioneuclideanAlgorithm(originalA,originalB){
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consta=Math.abs(originalA);
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constb=Math.abs(originalB);
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10-
if(a===0&&b===0){
11-
returnnull;
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}
13-
14-
if(a===0&&b!==0){
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returnb;
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}
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18-
if(a!==0&&b===0){
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returna;
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}
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22-
// Normally we need to do subtraction (a - b) but to prevent
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// recursion occurs to often we may shorten subtraction to (a % b).
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// Since (a % b) is normally means that we've subtracted b from a
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// many times until the difference became less then a.
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27-
if(a>b){
28-
returneuclideanAlgorithm(a%b,b);
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}
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31-
returneuclideanAlgorithm(b%a,a);
10+
return(b===0) ?a :euclideanAlgorithm(b,a%b);
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}

‎src/algorithms/math/is-power-of-two/__test__/isPowerOfTwo.test.js

Lines changed: 2 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,17 +1,10 @@
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importisPowerOfTwofrom'../isPowerOfTwo';
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describe('isPowerOfTwo',()=>{
4-
it('should throw an exception when trying to apply function to negative number',()=>{
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constisNegativePowerOfTwo=()=>{
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isPowerOfTwo(-1);
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};
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expect(isNegativePowerOfTwo).toThrowError();
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});
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it('should check if the number is made by multiplying twos',()=>{
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expect(isPowerOfTwo(-1)).toBeFalsy();
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expect(isPowerOfTwo(0)).toBeFalsy();
14-
expect(isPowerOfTwo(1)).toBeFalsy();
7+
expect(isPowerOfTwo(1)).toBeTruthy();
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expect(isPowerOfTwo(2)).toBeTruthy();
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expect(isPowerOfTwo(3)).toBeFalsy();
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expect(isPowerOfTwo(4)).toBeTruthy();

‎src/algorithms/math/is-power-of-two/__test__/isPowerOfTwoBitwise.test.js

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@@ -1,17 +1,10 @@
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importisPowerOfTwoBitwisefrom'../isPowerOfTwoBitwise';
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describe('isPowerOfTwoBitwise',()=>{
4-
it('should throw an exception when trying to apply function to negative number',()=>{
5-
constisNegativePowerOfTwo=()=>{
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isPowerOfTwoBitwise(-1);
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};
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expect(isNegativePowerOfTwo).toThrowError();
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});
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it('should check if the number is made by multiplying twos',()=>{
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expect(isPowerOfTwoBitwise(-1)).toBeFalsy();
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expect(isPowerOfTwoBitwise(0)).toBeFalsy();
14-
expect(isPowerOfTwoBitwise(1)).toBeFalsy();
7+
expect(isPowerOfTwoBitwise(1)).toBeTruthy();
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expect(isPowerOfTwoBitwise(2)).toBeTruthy();
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expect(isPowerOfTwoBitwise(3)).toBeFalsy();
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expect(isPowerOfTwoBitwise(4)).toBeTruthy();

‎src/algorithms/math/is-power-of-two/isPowerOfTwo.js

Lines changed: 2 additions & 7 deletions
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@@ -3,13 +3,8 @@
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*@return {boolean}
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*/
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exportdefaultfunctionisPowerOfTwo(number){
6-
// Don't work with negative numbers.
7-
if(number<0){
8-
thrownewError('Please provide positive number');
9-
}
10-
11-
// 0 and 1 are not powers of two.
12-
if(number<=1){
6+
// 1 (2^0) is the smallest power of two.
7+
if(number<1){
138
returnfalse;
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}
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‎src/algorithms/math/is-power-of-two/isPowerOfTwoBitwise.js

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@@ -3,13 +3,8 @@
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*@return {boolean}
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*/
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exportdefaultfunctionisPowerOfTwoBitwise(number){
6-
// Don't work with negative numbers.
7-
if(number<0){
8-
thrownewError('Please provide positive number');
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}
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// 0 and 1 are not powers of two.
12-
if(number<=1){
6+
// 1 (2^0) is the smallest power of two.
7+
if(number<1){
138
returnfalse;
149
}
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‎src/algorithms/math/least-common-multiple/leastCommonMultiple.js

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@@ -7,9 +7,5 @@ import euclideanAlgorithm from '../euclidean-algorithm/euclideanAlgorithm';
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*/
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99
exportdefaultfunctionleastCommonMultiple(a,b){
10-
if(a===0&&b===0){
11-
return0;
12-
}
13-
14-
returnMath.abs(a*b)/euclideanAlgorithm(a,b);
10+
return((a===0)||(b===0)) ?0 :Math.abs(a*b)/euclideanAlgorithm(a,b);
1511
}

‎src/algorithms/sets/fisher-yates/fisherYates.js

Lines changed: 1 addition & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -6,15 +6,9 @@ export default function fisherYates(originalArray) {
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// Clone array from preventing original array from modification (for testing purpose).
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constarray=originalArray.slice(0);
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9-
if(array.length<=1){
10-
returnarray;
11-
}
12-
139
for(leti=(array.length-1);i>0;i-=1){
1410
constrandomIndex=Math.floor(Math.random()*(i+1));
15-
consttmp=array[randomIndex];
16-
array[randomIndex]=array[i];
17-
array[i]=tmp;
11+
[array[i],array[randomIndex]]=[array[randomIndex],array[i]];
1812
}
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2014
returnarray;

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