Count Encodings

#include <bits/stdc++.h>
using namespace std;

/*
QUESTION - https://www.youtube.com/watch?v=jFZmBQ569So&list=PL-Jc9J83PIiG8fE6rj9F5a6uyQ5WPdqKy&index=20 (COUNT ENCODINGS)
*/

void getEncodings(string digits, string path, vector<char> &encoding){
    if(digits.empty()){
        cout << path << '\n';
        return;
    }
    // no encoding for '0', and no encoding for something like "03" as it is invalid
    if(digits[0] == '0'){
        return;
    }
    // level - encoding
    //options - digits to encode
    int oneChar = stoi(digits.substr(0, 1));
    getEncodings(digits.substr(1), path + encoding[oneChar], encoding);

    if(digits.size() >= 2){
        int twoChar = stoi(digits.substr(0, 2));
        if(twoChar > 0 && twoChar <= 26){
            getEncodings(digits.substr(2), path + encoding[twoChar], encoding);
        }
    }
}



int main() {
    // your code goes here
    string digits;
    cin >> digits;
    vector<char> encoding(27, -1);
    for(int i = 1; i < 27; i++){
        encoding[i] = (char) (i - 1) + 'a';
    }
    getEncodings(digits, "", encoding);

}