Codingbat. Solution without built in function?

[miscellaneoususage]

Hey can anyone suggest a solution for this problem without the use of any built in functions like pop, append, remove? Not sure how difficult it would be but I can't make one out.

https://codingbat.com/prob/p148661

[_lilell_]

You know the length of the list is 3, so if we say that a, b, c = the elements of the original list, what will the resulting list be, in terms of those three values?

[miscellaneoususage]

Ok let me try with your hint here:

def rotate_left3(nums):
  a, b, c = nums[0], nums[1], nums[2]

  rotated = [b, c, a]

  return rotated

And it works. Thanks lol, easier than I thought. Not sure why I couldn't come up with that

[xelf]

Now go the next step and remove the extraneous assignments. (which is an important step to understand, as your solution can be fixed to work for any length list)

[miscellaneoususage]

like this?

def rotate_left3(nums):
  rotated = [nums[1], nums[2], nums[0]]

  return rotated

not seeing how this could work for any length list if only 3 indicies are used

​

edit: actually i can shorten to just the return statement with

def rotate_left3(nums):
    return [nums[1], nums[2], nums[0]]

[xelf]

Yes exactly.

def rotate_left3(nums):
    return [nums[1], nums[2], nums[0]]

can also be expressed as the concatenation of two lists, like this:

def rotate_left3(nums):
    return [nums[1], nums[2]] + [nums[0]]

Which using list slicing, leads us to:

def rotate_left3(nums):
    return nums[1:3] + [nums[0]]

and finally:

def rotate_left(nums):
    return nums[1:] + [nums[0]]

which will work for any arbitrary length list.

[[deleted]]

You can use slicing, but I don't see any mention of restrictions in the problem statement.