81f8eb22f7
Updated the code to utilize `Array.from()` to check for factors, this can be shortened even further (follow-up commits)
1.7 KiB
1.7 KiB
factors
Returns the array of factors of the given int. If the second argument is set to true returns only the prime factors of int.If the third argument is set to true will return an array of arrays each containing two elements, the factor and the number of times the factor divides int.
If int is 1 or 0 returns an empty array.
If int is less than 0 returns all the factors of -int together with their additive inverses.
Note:- Negative numbers are not considered prime.
const factors = (int,prime = false,powers = false) => {
const howManyTimes = (num,divisor) => {
if([1,0].includes(divisor)) return Infinity
let i = 0
while(Number.isInteger(num/divisor)){
i++
num = num / divisor
}
return i
}
const isPrime = num => {
const boundary = Math.floor(Math.sqrt(num));
for (var i = 2; i <= boundary; i++) if (num % i === 0) return false;
return num >= 2
}
let isNeg = int < 0;
int = isNeg ? -int : int;
let array = Array.from({length: int - 1}).map((val,i) => int % (i+2) === 0 ? (i+2) : false).filter(val => val);
if(isNeg) array = array.reduce((acc,val) => {acc.push(val); acc.push(-val); return acc}, []);
array = prime ? array.filter(el => isPrime(el)) : array;
return powers ? array.map(x => [x,howManyTimes(int,x)]) : array
}
factors(12); //[2,3,4,6,12]
factors(12,true); //[2,3]
factors(12,true,true); //[[2,2], [3,1]]
factors(12,false,true); //[[2,2], [3,1], [4,1], [6,1], [12,1]]
factors(-12); //[2, -2, 3, -3, 4, -4, 6, -6, 12, -12]
factors(12,true); //[2,3]
factors(12,true,true); //[[2,2], [3,1]]
factors(12,false,true); //[[2,2], [-2,2], [3,1], [-3,1], [4,1], [-4,1], [6,1], [-6,1], [12,1], [-12,1]]