Problem
We are required to write a JavaScript function that takes in a positive integer. Our function should represent this number as the sum of some powers of prime numbers.
Therefore, for the number n, our function should return a string like this −
n = "(p1**n1)(p2**n2)...(pk**nk)"
Where p1, p2, p3..pk are prime numbers and n1, n2,..nk are their non-negative powers and a ** b stands for a raised to the power b.
Example
Following is the code −
const isPrime = num => { for(let i = 2; i < num; i++){ if(num % i === 0){ return false; } }; return num > 1; } const count = (arr = [], n = 1) => { for(const k in arr){ if(n % k === 0){ arr[k] += 1; return count(arr, n / k) } }; return arr; }; const primeFactors = (n) => { const res = []; for(let i = 2; i < n; i++){ if(isPrime(i)){ res.push(i); } }; const arr = []; for(const el in res){ arr[el] = 0; }; count(arr,n); let str = ''; for(const x in arr){ if(arr[x] > 1){ str += '(%s**%s)' %(x,arr[x]) }else if(arr[x] === 1){ str += '(%s)' % (x) }; }; return str }; console.log(primeFactors(86240));
Output
(2**5)(5)(7**2)(11)