The Min Perimeter Rectangle challenge brings us back to a lot of math. I had a gut feeling on this one and I only checked with a few examples but the minimum perimeter of a rectangle for a given area happens when the rectangle is in fact a square.

For those of you who want a to be 100% sure of this, here is a proper demonstration.

So all we need to do in this case is to find the closest integer number to the square root which is a dividing factor for the given area.

## Solution in Javascript with O(sqrt(N)) complexity

```
function solution(N) {
// write your code in JavaScript (Node.js 8.9.4)
for (let i = Math.floor(Math.sqrt(N)); i > 0; i--) {
if (N % i === 0) {
return (i + N / i) * 2;
}
}
}
```

And that’s it.

Here you can see how it works and the full description of the problem.