i have tried the medium part but i couldnt get it solved so i am asking if you have some people that can solve this recursive question
here is a question and i have a very similar code but i need to convert it some how in order to fit this question
question: In order to make their phone numbers more memorable, service providers like to find numbers that spell out some word (called a mnemonic) appropriate to their business that makes that phone number easier to remember. For example, the phone number for a recorded time-of-day message in some localities is 637-8687 (NERVOUS). Imagine that you have just been hired by a local telephone company to write a method listMnemonics that will generate all possible letter combinations that correspond to a given number, represented as a string of digits. For example, if you call recursiveObject.listMnemonics("723") your method shall generate and print out (using recursion) the following 27 possible letter combinations that correspond to that prefix: PAD PBD PCD RAD RBD RCD SAD SBD SCD PAE PBE PCE RAE RBE RCE SAE SBE SCE PAF PBF PCF RAF RBF RCF SAF SBF SCF
notice that always every char come from a different group for each uniq group of letters we have its reprasentative number my efforts in solving it: i know that in order to solve this question is need to use a recursive methos that prints out all the subsets of a given string letters with a given resolt string size