Get Kpc

 1. You are given a string str. The string str will contains numbers only, where each number stands for a key pressed on a mobile phone.

2. The following list is the key to characters map :
    0 -> .;
    1 -> abc
    2 -> def
    3 -> ghi
    4 -> jkl
    5 -> mno
    6 -> pqrs
    7 -> tu
    8 -> vwx
    9 -> yz
3. Complete the body of getKPC function - without changing signature - to get the list of all words that could be produced by the keys in str.
Use sample input and output to take idea about output.

Input Format

A string str

Output Format

Contents of the arraylist containing words as shown in sample output

Constraints
0 <= str.length <= 10
str contains numbers only
Sample Input
78
Sample Output
[tv, tw, tx, uv, uw, ux]

Solution:

import java.io.*;

import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);

        String str = sc.nextLine();

        ArrayList<String> res = getKPC(str);

        System.out.println(res);

    }

    static String code[] = {".;","abc","def","ghi","jkl","mno","pqrs","tu","vwx","yz"};

    public static ArrayList<String> getKPC(String str) {

        ArrayList<String> res = new ArrayList<>();

        if(str.length() ==0){

            res.add("");

            return res;

        }

        

        char ch = str.charAt(0);

        

        ArrayList<String> ires = getKPC(str.substring(1));

        String strCode = code[ch - '0'];

        for(int i=0;i<strCode.length();i++){

            char c = strCode.charAt(i);

            for(String s:ires)

                res.add(c+s);

        }

        

        return res;

    }

}