Add pronic number implementation

[itsAkshayDubey]

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Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
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[raklaptudirm]

Format your code using standard.js. Read the CONTRIBUTING.md before contributing.

[appgurueu]

The current implementation is very odd: (1) you don't need to check whether numbers are odd if your equation works (2) your equation is unnecessarily convoluted.

[itsAkshayDubey]

The current implementation is very odd: (1) you don't need to check whether numbers are odd if your equation works (2) your equation is unnecessarily convoluted.

Refactored it, have a look.

[appgurueu]

Why use Math.round if you can use Math.floor/Math.ceil? I also failed to consider edge cases properly: 0 is pronic but 1 is not. The following should work:

if (number === 0) return true
const sqrt = Math.sqrt(number)
return sqrt % 1 !== 0 && Math.ceil(sqrt) * Math.floor(sqrt) === number

Please extend the tests to check all example numbers listed on https://oeis.org/A002378 - it's easy to mess up some edge cases. Also check that all other numbers in the range aren't false positives.

[itsAkshayDubey]

Why use Math.round if you can use Math.floor/Math.ceil? I also failed to consider edge cases properly: 0 is pronic but 1 is not. The following should work:

if (number === 0) return true
const sqrt = Math.sqrt(number)
return sqrt % 1 !== 0 && Math.ceil(sqrt) * Math.floor(sqrt) === number

Please extend the tests to check all example numbers listed on https://oeis.org/A002378 - it's easy to mess up some edge cases. Also check that all other numbers in the range aren't false positives.

Added, have a look.