Print Keypad combination problem using JavaScript

Hello guys, today we will do the medium-level question of recursion. You can do this question with recursion as well as an iterative method but iterative is a bit hard. If you do not familiar with recursion then go and checkout recursion in javascript post. Now come to the question…

You have given a string containing digits from 2 to 9, you have to print all the possible letter combinations that the given number represents in string using JavaScript

It is similar to keypad phone keys.

You need to map the digits to the particular letters(just like shown in the keypad phone).

Note: ‘0’ is not mapping with anything.

Examples:

Input:”8″

Output:

t
u
v

Input: “78”
output:

pt
pu
pv
qt
qu
qv
rt
ru
rv
st
su
sv

Algorithm to print all possible strings generated from given keypad of phone

Here, we”ll use recursion.

1. Create an array to store all characters correspond to digit in the keyboard.

2. Base case: if string length becomes ‘zero’ then print our output string.

3. We store words in the ‘ans’ string.

4. Take out the character from the string using the charAt() function and concatenate with ans string using ‘+’.

4. Try all possible characters which correspond to the current digit and recursion for the remaining digits.

let code=["",",;","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"];
function kpc(str,ans){
  // base
  if(str.length==0){
    console.log(ans);
    return ;
  }
  
  let ch=code[parseInt(str.charAt(0))];
  let s=str.substring(1);
  for(let i=0;i<ch.length;i++){
    let c=ch.charAt(i);
    //function call
    kpc(s,ans+c);
  }
  
}
kpc("234","");

Output:

adg
adh
adi
aeg
aeh
aei
afg
afh
afi
bdg
bdh
bdi
beg
beh
bei
bfg
bfh
bfi
cdg
cdh
cdi
ceg
ceh
cei
cfg
cfh
cfi