Sure, go ahead. I am not a proper sensei yet, I guess.

It still seems to have an issue with random tests (in Ruby)
The checking code (as someone suggested already) is using the target twice. But the function is being feed with the correct start value.

Rand test 1

[[0, 4], [4, -6]]

wrong route from [4, -6] to [4, -6]

Expected: [[4, -6]],

instead got: [[0, 4], [1, 3], [2, 2], [3, 1], [4, 0], [4, -1], [4, -2], [4, -3], [4, -4], [4, -5], [4, -6]]

Rand test 2

[[1, -6], [4, 2]]

wrong route from [4, 2] to [4, 2]

Expected: [[4, 2]],

instead got: [[1, -6], [2, -5], [3, -4], [4, -3], [4, -2], [4, -1], [4, 0], [4, 1], [4, 2]]

Thank you for your input

Yes, it is indeed reversed. Embarrassing.