Get the previous prüfer code for the given code. If the given code is the first code for its node count, the last code of the previous node count is returned. When node count reaches 2, I.e.: code count is 0, we stop and return the input unchanged.
Get the previous prüfer code for the given code. If the given code is the first code for its node count, the last code of the previous node count is returned. When node count reaches 2, I.e.: code count is 0, we stop and return the input unchanged.