-
Notifications
You must be signed in to change notification settings - Fork 4
/
primesInNumbers.js
50 lines (45 loc) · 1.03 KB
/
primesInNumbers.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
/**
* Description:
*
* Given a positive number n > 1 find the prime factor decomposition of n.
* The result will be a string with the following form :
*
* "(p1**n1)(p2**n2)...(pk**nk)"
* with the p(i) in increasing order and n(i) empty if n(i) is 1.
*
* Example: n = 86240 should return "(2**5)(5)(7**2)(11)"
*
*/
function primeFactors(n) {
let i = 2, obj = {}, result = ''
while (i <= n) {
if (n % i === 0) {
n /= i;
obj[i] = obj[i] ? obj[i] + 1 : 1
}
else {
i = nextPrime(i)
}
}
for (key in obj) {
result += obj[key] === 1
? `(${key})`
: `(${key}**${obj[key]})`
}
return result
}
function nextPrime(value) {
if (value > 2) {
let i, q;
do {
i = 3;
value += 2;
q = Math.floor(Math.sqrt(value));
while (i <= q && value % i) {
i += 2;
}
} while (i <= q);
return value;
}
return value === 2 ? 3 : 2;
}