Optimize 002.go so that it executes within the time limit

[ameykhale]

The current solution passes all but one test case, where it fails as it takes too long to execute. Optimize it so that it executes within the time limit.

[ananichev]

Let me take this one

[tgreenhalgh]

@funoctis are you going to include other problems? This looks like a fun project to contribute to!
Also, where are you running the test cases?

[ameykhale]

@tgreenhalgh Directly on HackerRank at the moment because I don't really know how big their test cases are, but we could add local tests of our own

Yes I'm planning to include more problems, will merge PRs for added problems once I can test they pass most if not all test cases on HackerRank