Write a function that accepts two arguments, arr and offset:

• arr and offset are both arrays containing N elements where N is greater than 0
• offset contains only integer values

The function should return an array where each non nil value in arr is shifted by the amount given at the same index in offset.

arr = [1, nil, nil]
offset = [1, 0, 0]
# shift arr[0] to arr[1]
# ignore offset[1] since arr[1] was initially nil
# ignore offset[2] since arr[2] is nil
result = [nil, 1, nil]

Two values cannot be shifted into the same index nor can a value be shifted to an index that is already occupied by a non nil value that will not be moved.

arr = [1, nil, 2]
offset = [1, 0, -1]
# offset[0] and offset[2] cancel out because they would move items to the same index
result = [1, nil, 2]

arr = [1, 2, nil]
offset = [1, -1, 0]
# offset[0] and offset[1] are allowed to swap since both items will move
result = [2, 1, nil]

See the test cases in spec/rearrange_spec.rb for a more comprehensive list of examples.

bundle
rspec -fd