Question

Given an array:

a = [1, 2, 3, 4, 5, 6]

I want to rotate elements i through j in some direction n times. So, for example:

i = 2
j = 3
n = 1

Rotating a will produce:

new_a = [1, 2, 4, 3, 5, 6]

This is what I have:

def rotate_sub(a, i, j, n)
  return a[0...i] + a[i..j].rotate(n) + a[j+1..-1]
end

Is there a better way to do this? Since there is no bound-checks, i or j could very well be outside the bounds of the array.

Answer 1

I don’t think there’s a magical way, so perhaps the simplest is the best:

def rotate_sub(a, i, j, n)
  a[0...i] + a[i..j].rotate(n) + a[j+1..-1] if i < j && j < a.size
end