getkeypadcomb.java

import java.util.*;
public class getkeypadcomb {
    public static void main(String[] args) {
        Scanner sc= new Scanner(System.in);
        String str= sc.next();
        ArrayList<String> words= getKPC(str);
        System.out.println(words);

        
    }
    public static String[] codes= {".;" ,"abc","def","ghi","jkl","mno","pqrs","tu","vwx","yz"};
    public static ArrayList<String> getKPC(String str){

       if(str.length()==0){
         ArrayList<String> bres =new ArrayList<>();
            bres.add("");
             return bres;



       }
       char ch = str.charAt(0);
       String ros= str.substring(1, ch);
       ArrayList<String> rres= getKPC(ros);
       ArrayList<String> mres= new ArrayList<>();
       String codeforch= codes[ch];
       for(int i =0 ; i<codeforch.length();i++){
        char chcode=codeforch.charAt(i);
        for(String rstr:rres){
            mres.add(chcode+rstr);

        }
       }
       return mres;
    }
}