The editorial is overcomplicated.There are no flexible bits. The case keep_ok = true and flip_ok = true does not exist for any x != 0. In short, without spoiling a solution, the elements we need to flip are (forced/) fixed as soon as we look at the right bit.

In the editorial it should be n > 2: For all integers n > 2, the inequality ... holds.

On "Suggest Change" I submitted a tutorial for english for this change. I am not certain if that's the correct way to give feedback to the editorials.