Submit solution

Points:
30 (partial)

Time limit:
2.0s

Memory limit:
256M

Author:

Problem type

Allowed languages

C
, C++
, Pascal
, Rust

For a while now, ~~show off~~ demonstrate his fast multiplication code, has created a problem that really tests the accuracy and speed of your fast multiplication code.

#### Input Specification

The first line of input will have .

The second line of input will have .

Both and will be non-negative integers strictly less than .

#### Output Specification

Output the product .

#### Sample Input

```
123456123456123456123456123456123456
987987876876765765654654543543432432321321
```

#### Sample Output

`121973153300851295215956247283945278187966162014464020099359068031370037005376`

## Comments

So close... any tips on improving Karatsuba?

Well Karatsuba was not the intended solution...

Yeah I initially wanted to implement FFT but it didn't quite workout, any idea on how to avoid overflow in NTT, choosing a modulo bigger then then multiplication overflows but if I choose a modulo smaller then (for example ) then the result is incorrect (or I can take base which TLE's).

No JAVA?

read the comment right below you.

V V V V V

Why not JAVA? Isn't BigInteger capable of processing numbers of any range?

Funny thing; I was reading the Java BigInteger documentation, and the fastest multiplication method would take 6 seconds on a worst case.

That is precisely why Java is disallowed.

Couldn't we disable bigInteger and bigDecimal like a + b hard?

There exists a certain

`com.sun.media.sound.FFT`

, which would trivialize the problem. As we currently do not trivially support the banning of arbitrary packages, Java will continue to be banned.yes i agree

I think the reason why it was not allowed later on was because Java is a lot slower than the currently allowed languages; now that custom language limits are allowed, someone needs to write a correct Java solution and then the Time Limits might be set accordingly.

You could always bug Kirito via slack for these things btw, he undoubtedly enjoys it.

As a side note, the current TL is probably too lenient as well because the judges are a lot faster now than they were ~3 yrs ago. (So maybe even Java can pass on the judge with these TLs)

Time limit lowered to 2s. Karatsuba shall not pass!

My Karatsuba pass the tests, even faster than some FFTs implementations.