Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases. Notes: It is intended for this problem to be ...

Characters ('a' to 'i') are represented by ('1' to '9') respectively. Characters ('j' to 'z') are represented by ('10#' to '26#') respectively. Return the string formed after mapping. It's guaranteed ...