?

I got pretty similar result ~ 3.6s

I'm stuck on 58!

theDarkBright, I just ran your solution now (twice) and it ran for 4.7 secs. Maybe server load plays a role. I ran mine also, and it runs in 0.7 secs. So there is still room for improvement. I also don't think my implementation is the most optimal one.

lol wish I saw this before I started fixing mine, cause I had the same bug.. (java)

I'm glad you figured it out & liked it.

TDRS

The description says:

A natural number is called k-prime if it has exactly k prime factors, counted with multiplicity.

4 = 2 * 2 is 2-prime since he has two prime factors (the prime 2 is not unique: 2 has multiplicity 2 since the prime 2 appears 2 times)
6 = 2 * 3 is 2-prime since he has two prime factors (2 and 3)
8 = 2 * 2 * 2 is 3-prime since 2 is prime and its multiplicity (= number of times it appears) is 3
12 = 2 * 2 * 3 is 3-prime since he has 2 prime factors (2 and 3 but 2 appears 2 times)
48 = 2 * 2 * 2 * 2 * 3 is 5-prime: 2 appears 4 times and 3 once
Note: 1 is not a prime factor because 1 is not a prime.

prime factors, not unique prime factors

You need a O(n) to O(log n) solution ;-)

Old kata rankings are almost always overranked.

It is not correct. (-1)^2 != -1^2

Its -7^2*2 not (-7)^2*2 so the 7^2 is calculated before the minus sign.
Therefore,

-> -7^2*2
-> -49*2  (7^2) is calculated before the minus sign
-> -98

• do the error check on the fly. For now, you're iterating the input one extra time just for that.
• iterators (for (char c: input.toCharArray()) ...) are "slow" by essence (but it's possible to achieve the task if you use it only one time).
• replaceAll is slow (uses regexp). If you use it, make only one call.
• append elements in one block, not in three separated actions.

EDIT: too late... x-)

Ah.

No, no can do.

Sorry.

Go to tab Solutions, and click on the button?